Electrochemical energy storage devices

ABSTRACT

Provided herein are energy storage devices. In some cases, the energy storage devices are capable of being transported on a vehicle and storing a large amount of energy. An energy storage device is provided comprising at least one liquid metal electrode, an energy storage capacity of at least about 1 MWh and a response time less than or equal to about 100 milliseconds (ms).

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.15/647,468, filed Jul. 12, 2017, which is a continuation-in-partapplication of U.S. patent application Ser. No. 14/688,179, filed Apr.16, 2015 (now U.S. Pat. No. 9,735,450), which is a continuation of PCTApplication No. PCT/US2013/065092, filed Oct. 15, 2013, which claims thebenefit of U.S. Provisional Application No. 61/715,821, filed Oct. 18,2012, and which is a continuation-in-part of U.S. patent applicationSer. No. 13/801,333, filed Mar. 13, 2013 (now U.S. Pat. No. 9,312,522),which claims the benefit of U.S. Provisional Application No. 61/763,925,filed Feb. 12, 2013, and U.S. Provisional Application No. 61/715,821,filed Oct. 18, 2012, and a continuation-in-part of U.S. patentapplication Ser. No. 14/536,563, filed Nov. 7, 2014 (now U.S. Pat. No.9,728,814), which is a continuation of U.S. patent application Ser. No.14/178,806. filed Feb. 12, 2014, (now U.S. Pat. No. 9,520,618), whichclaims the benefit of U.S. Provisional Application No. 61/763,925, filedFeb. 12, 2013, each of which is entirely incorporated herein byreference.

BACKGROUND

A battery can be a device capable of converting stored chemical energyinto electrical energy. Batteries can be used in many household andindustrial applications. In some instances, batteries are rechargeablesuch that electrical energy is capable of being stored in the battery aschemical energy (i.e., charging the battery). The battery can be coupledto a load (e.g., electrical appliance) and employed for use inperforming work.

SUMMARY

The present disclosure recognizes a need for energy storage devices(e.g., batteries) that are capable of storing a large amount of energyand are transportable on a vehicle (e.g., truck). Several aspects of theenergy storage devices are described.

An aspect of the present disclosure provides an energy storage devicecomprising at least one liquid metal electrode, wherein the energystorage device has an energy storage capacity of at least about 1 kWhand a response time less than or equal to about 100 milliseconds (ms).

Another aspect of the present disclosure provides an energy storagedevice comprising at least one liquid metal electrode stored in acontainer at a temperature greater than or equal to about 250° C.,wherein the energy storage device has an energy storage capacity of atleast about 1 kWh, and wherein the container has a surfacearea-to-volume ratio that is less than or equal to about 100 m⁻¹.

Another aspect of the present disclosure provides an energy storagedevice comprising at least one liquid metal electrode, wherein theenergy storage device maintains at least 90% of its energy storagecapacity after 100 charge/discharge cycles, and wherein the energystorage device has an energy storage capacity of at least about 1 kWh.

Another aspect of the present disclosure provides an energy storagedevice comprising at least one liquid metal electrode, wherein thedevice is transportable on a vehicle and has an energy storage capacityof at least about 1 kWh, and wherein the energy storage device istransportable with at least any two of an anode, cathode and electrolyteof the energy storage device in solid state.

Another aspect of the present disclosure provides an energy storagedevice comprising a container containing one or more cells, anindividual cell of the one or more cells containing at least one liquidmetal electrode, wherein a rate of heat generation in the cell duringcharge/discharge is about equal to a rate of heat loss from the cell.

Another aspect of the present disclosure provides a separator-lessenergy storage device comprising a container with at least one liquidmetal electrode, wherein the container has a surface area-to-volumeratio that is less than or equal to about 100 m⁻¹, and theseparator-less energy storage device has (i) a response time less thanor equal to about 100 milliseconds (ms), and/or (ii) an energy storagecapacity of at least about 1 kWh.

Another aspect of the present disclosure provides a method for formingan energy storage device, comprising shipping a container comprising anenergy storage material in solid state to a destination location, and atthe destination location supplying energy to the energy storage materialto form at least one of a liquid metal anode, liquid metal cathode, andliquid electrolyte, thereby forming the energy storage device.

Another aspect of the present disclosure provides an energy storagesystem, comprising: (a) a container comprising one or more energystorage cells, wherein an individual energy storage cell of the one ormore energy storage cells comprises an energy storage materialcomprising at least one liquid metal electrode; and (b) a control systemcomprising a processor with machine-executable code for monitoring atleast one temperature of the one or more energy storage cells and/or thecontainer, wherein the processor regulates the flow of electrical energyinto at least a subset of the one or more energy storage cells such thatthe energy storage material undergoes sustained self heating duringcharge/discharge.

Another aspect of the present disclosure provides an energy storagedevice comprising at least one electrochemical cell having an operatingtemperature, the at least one electrochemical cell comprising: (a) aliquid negative electrode comprising a first metal; (b) a liquidelectrolyte adjacent to the liquid negative electrode; and (c) a liquidpositive electrode adjacent to the liquid electrolyte, the liquidpositive electrode comprising a second elemental metal that is differentthan the first metal, wherein the liquid electrolyte comprises a chargedspecies of the first metal and an oppositely charged species of thesecond metal, and wherein the energy storage device is capable of beingtransported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a molten salt, wherein a liquid electronic conductoris extracted from the molten salt by oxidation and metal is extractedfrom the molten salt by reduction, and wherein the energy storage deviceis capable of being transported on a vehicle.

Another aspect of the present disclosure provides anelectrometallurgical cell comprising a positive electrode and a negativeelectrode, wherein the electrodes are liquid, the reactants of reactionsthat occur at the electrodes are liquid, and the products of reactionsthat occur at the electrodes are liquid, and wherein theelectrometallurgical cell is capable of being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice capable of being transported on a vehicle and having a powercapacity of greater than 1 MW and: (a) a physical footprint smaller thanabout 100 m²/MW; (b) a cycle life greater than 3000 deep dischargecycles; (c) a lifespan of at least 10 years; (d) a DC-to-DC efficiencyof at least 65%; (e) a discharge capacity of at most 10 hours; and (f) aresponse time of less than 100 milliseconds.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid electrode, the electrode comprising anadditive, wherein the electrode is consumed and the additive isconcentrated by operation of the device, and wherein a property of thedevice is determined by of the concentration of the additive, andwherein the energy storage device is capable of being transported on avehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid antimony electrode, a steel container and alayer of iron antimonide disposed therebetween, wherein the device isoperated at less than 738° C., and wherein the energy storage device iscapable of being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid electrode and a current collector in contactwith the electrode, wherein the liquid electrode is consumed in areaction during operation of the device, and wherein the amount ofliquid electrode is in stoichiometric excess relative to other reactantsof the reaction such that the current collector is in contact with theliquid electrode when the reaction has proceeded to completion, andwherein the energy storage device is capable of being transported on avehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising an alkaline earth metal present in each of a positiveelectrode, a negative electrode and a liquid electrolyte, wherein theenergy storage device is capable of being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising an alkaline earth metal present in each of anelemental form, an alloy form and a halide form, wherein the energystorage device is capable of being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid anode, a liquid cathode and a liquidelectrolyte disposed therebetween, wherein the thickness of theelectrolyte is substantially constant through a charge-discharge cycleof the device, and wherein the energy storage device is capable of beingtransported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid anode, a liquid cathode and a liquidelectrolyte disposed therebetween, wherein the thickness of theelectrolyte is less than 50% of the thickness of the cathode or theanode, and wherein the energy storage device is capable of beingtransported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid electrode comprising an elemental alkalineearth metal and an electrolyte comprising a halide of the alkaline earthmetal, wherein the electrolyte further comprises complexing ligands, andwherein the energy storage device is capable of being transported on avehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a conductive housing comprising a conductive liquidanode, a conductive liquid cathode and an electrolyte disposedtherebetween, wherein the interior surface of the container is notelectrically insulated, and wherein the energy storage device is capableof being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising an anode comprising a first electronically conductiveliquid and a cathode comprising a second electronically conductiveliquid, wherein the device is configured to impede mixing of theelectronically conductive liquids, and wherein the energy storage deviceis capable of being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a negative electrode comprising an alkali metal, apositive electrode comprising the alkali metal and one or moreadditional elements and a liquid electrolyte disposed between theelectrodes, wherein the electrolyte is not depleted upon charging ordischarging of the device, and wherein the energy storage device iscapable of being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid metal electrode, a second metal electrodethat is a liquid and an electrolyte disposed between the electrodes,wherein the electrolyte is a paste, and wherein the energy storagedevice is capable of being transported on a vehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid negative electrode comprising an alkalimetal, a liquid positive electrode comprising an alloy of the alkalimetal and an electrolyte disposed between the electrodes, wherein theelectrolyte comprises a salt of the alkali metal and particles, andwherein the energy storage device is capable of being transported on avehicle.

Another aspect of the present disclosure provides an energy storagedevice comprising a metal anode, a metal cathode and an electrolytedisposed between the electrodes, wherein the anode, cathode andelectrolyte are liquids at an operating temperature of the device andthe operating temperature of the device is less than 500° C., andwherein the energy storage device is capable of being transported on avehicle.

Another aspect of the present disclosure provides a method for chargingan energy storage device comprising connecting an external chargingcircuit to terminals of the energy storage device that is capable ofbeing transported on a vehicle such that an active alkali metal movesfrom a positive electrode, through an electrolyte, to a negativeelectrode comprising a metal having a higher chemical potential than thepositive electrode.

Another aspect of the present disclosure provides a method fordischarging an energy storage device comprising connecting an externalload to terminals of the energy storage device that is capable of beingtransported on a vehicle such that an active alkali metal moves from anegative electrode, through an electrolyte as cations, to a positiveelectrode where the active alkali metal forms a neutral metal having alower chemical potential than the negative electrode.

Another aspect of the present disclosure provides an energy storagedevice comprising a liquid metal electrode, an electrolyte and a currentcollector in contact with the electrode, wherein the current collectorcomprises a material that has a greater wetability with the liquid metalthan with the electrolyte.

Another aspect of the present disclosure provides an electrochemicalenergy storage device comprising an anode, a cathode and an electrolytebetween said anode and said cathode, wherein the device is not capableof conducting ions through said electrolyte at a first temperature, andwherein the device is capable of conducting ions through saidelectrolyte at a second temperature that is greater than said firsttemperature, and wherein said device is configured to be transported atthe first temperature at a potential difference between said anode andsaid cathode that is less than 1 volt.

Another aspect of the present disclosure provides an electrochemicalenergy storage device comprising a negative electrode and a positiveelectrode and an electrolyte disposed between said negative and positiveelectrodes, wherein the electrochemical energy storage device has afirst potential difference between the negative and positive electrodesat a first temperature that is less than about 50° C. and a secondpotential difference between the negative and positive electrodes at asecond temperature of at least about 250° C., wherein the secondpotential difference is greater than the first potential difference.

Another aspect of the present disclosure provides a method for formingan energy storage system, comprising: (a) forming, at a first location,an energy storage device comprising a negative electrode and a positiveelectrode, and an electrolyte between the negative electrode and thepositive electrode, wherein the negative electrode, positive electrodeand electrolyte are in the liquid at an operating temperature of theenergy storage device; and (b) placing the energy storage device on avehicle that is configured to transport the energy storage device fromthe first location to a second location.

Additional aspects and advantages of the present disclosure will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only illustrative embodiments of thepresent disclosure are shown and described. As will be realized, thepresent disclosure is capable of other and different embodiments, andits several details are capable of modifications in various obviousrespects, all without departing from the disclosure. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings or figures (also “FIG.” and “FIGs.” herein), ofwhich:

FIG. 1 is a illustration of an electrochemical cell (A) and acompilation (i.e., battery) of electrochemical cells (B and C);

FIG. 2 is a schematic cross sectional illustration of a battery housinghaving a conductor in electrical communication with a current collectorpass through an aperture in the housing;

FIG. 3 is a cross-sectional side view of an electrochemical cell orbattery;

FIG. 4 is a cross-sectional side view of an electrochemical cell orbattery with an intermetallic layer;

FIG. 5 is a cross-sectional side view of an electrochemical cell orbattery with a pressure relief structure;

FIGS. 6A and 6B are cross-sectional side and bottom views ofelectrochemical cells or batteries with alternative pressure reliefstructures;

FIG. 7A is a cross-sectional side view of an electrochemical cell orbattery with a bowing or bulging solid intermetallic layer;

FIG. 7B is a cross-sectional side view of the electrochemical cell orbattery with a post;

FIG. 7C is a cross-sectional side view of the electrochemical cell orbattery with ridges;

FIG. 8 is an illustration of a computer system;

FIG. 9 is an illustration of an electrochemical energy storage devicebeing transported on a truck; and

FIG. 10 illustrates a method for forming an energy storage system.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and describedherein, it will be obvious to those skilled in the art that suchembodiments are provided by way of example only. Numerous variations,changes, and substitutions may occur to those skilled in the art withoutdeparting from the invention. It should be understood that variousalternatives to the embodiments of the invention described herein may beemployed.

The term “surface area,” as used herein, generally refers to thegeometric surface area of an object.

The term “vehicle,” as used herein, generally refers to a car, truck,train, motorcycle, helicopter, plane, ship, boat, or robot. A vehiclecan be manned or unmanned. A vehicle can be configured to travel alone aroad or other pathway, such as a waterway. A vehicle can be coupled to atrailer or other container that is configured to house an energy storagedevice or a container having the energy storage device.

The term “cell,” as used herein, generally refers to an electrochemicalcell. A cell can include a negative electrode of material ‘A’ and apositive electrode of material ‘B’, denoted as A∥B. The positive andnegative electrodes can be separated by an electrolyte.

The term “module,” as used herein, generally refers to cells that areattached together in parallel by, for example, mechanically connectingthe cell housing of one cell with the cell housing of an adjacent cell(e.g., cells that are connected together in an approximately horizontalpacking plane). A module can include a plurality of cells in parallel. Amodule can comprise any number of cells (e.g., 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more). In some cases, amodule comprises 9, 12, or 16 cells. In some cases, a module is capableof storing about 700 Watt-hours of energy and/or delivering about 175Watts of power.

The term “pack,” as used herein, generally refers to modules that areattached through different electrical connections (e.g., vertically). Apack can comprise any number of modules (e.g., 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more). In some cases,a pack comprises 3 modules. In some cases, a pack is capable of storingabout 2 kilo-Watt-hours of energy and/or delivering about 0.5 kilo-Wattsof power.

The term “core,” as used herein generally refers to a plurality ofmodules or packs that are attached through different electricalconnections (e.g., in series and/or parallel). A core can comprise anynumber of modules or packs (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, or more). In some cases, the core alsocomprises mechanical, electrical, and thermal systems that allow thecore to efficiently store and return electrical energy in a controlledmanner. In some cases, a core comprises 12 packs. In some cases, a coreis capable of storing about 25 kilo-Watt-hours of energy and/ordelivering about 6.25 kilo-Watts of power.

The term “pod,” as used herein, generally refers to a plurality of coresthat are attached through different electrical connections (e.g., inseries and/or parallel). A pod can comprise any number of cores (e.g.,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,or more). In some cases, the pod contains cores that are connected inparallel with appropriate by-pass electronic circuitry, thus enabling acore to be disconnected while continuing to allow the other cores tostore and return energy. In some cases, a pod comprises 4 cores. In somecases, a pod is capable of storing about 100 kilo-Watt-hours of energyand/or delivering about 25 kilo-Watts of power.

The term “system,” as used herein, generally refers to a plurality ofcores or pods that are attached through different electrical connections(e.g., in series and/or parallel). A system can comprise any number ofcores or pods (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, 20, or more). In some cases, a system comprises 20 pods. Insome cases, a system is capable of storing about 2 megawatt-hours ofenergy and/or delivering about 500 kilowatts of power.

The term “battery,” as used herein, generally refers to one or moreelectrochemical cells connected in series and/or parallel. A battery cancomprise any number of electrochemical cells, modules, packs, cores,pods or systems.

Electrochemical Energy Storage Cells, Devices and Systems

The disclosure provides electrochemical energy storage devices(batteries) and systems. An electrochemical energy storage devicegenerally includes at least one electrochemical cell, also “cell” and“battery cell” herein, sealed (e.g., hermetically sealed) within ahousing.

An electrochemical cell of the disclosure may include a negativeelectrode, an electrolyte adjacent to the negative electrode, and apositive electrode adjacent to the electrolyte. The negative electrodecan be separated from the positive electrode by the electrolyte. Thenegative electrode can be an anode during discharging. The positiveelectrode can be a cathode during discharging. In some examples, anelectrochemical cell is a liquid metal battery cell. In some examples, aliquid metal battery cell can include a liquid electrolyte arrangedbetween a negative liquid (e.g., molten) metal electrode and a positiveliquid (e.g., molten) metal, metalloid and/or non-metal electrode. Insome cases, a liquid metal battery cell has a molten alkali metal (e.g.,lithium, magnesium, sodium) negative electrode, an electrolyte, and amolten metal positive electrode. The molten metal positive electrode caninclude one or more of tin, lead, bismuth, antimony, tellurium andselenium. Any description of a metal or molten metal positive electrode,or a positive electrode, herein may refer to an electrode including oneor more of a metal, a metalloid and a non-metal. The positive electrodemay contain one or more of the listed examples of materials. In anexample, the molten metal positive electrode can include lead andantimony. In some examples, the molten metal positive electrode mayinclude an alkali metal alloyed in the positive electrode.

In some examples, an electrochemical energy storage device includes aliquid metal negative electrode, a liquid metal positive electrode, anda liquid metal electrolyte separating the liquid metal negativeelectrode and the liquid metal positive electrode. The negativeelectrode can include an alkali metal, such as lithium, sodium,potassium, rubidium, cesium, or combinations thereof. The positiveelectrode can include elements selected from Group IIIA, IVA, VA and VIAof the periodic table of the elements, such as aluminum, gallium,indium, silicon, germanium, tin, lead, pnicogens (e.g., arsenic, bismuthand antimony), chalcogens (e.g., tellurium and selenium), orcombinations thereof. The electrolyte can include a salt (e.g., moltensalt), such as an alkali metal salt. The alkali metal salt can be ahalide, such as a fluoride, chloride, bromide, or iodide of the activealkali metal, or combinations thereof. In an example, the electrolyteincludes lithium chloride. As an alternative, the salt of the activealkali metal can be, for example, a non-chloride halide, bistriflimide,fluorosulfano-amine, perchlorate, hexaflourophosphate,tetrafluoroborate, carbonate, hydroxide, or combinations thereof.

In some cases, the negative electrode and the positive electrode of anelectrochemical energy storage device are in the liquid state at anoperating temperature of the energy storage device. To maintain theelectrodes in the liquid states, the battery cell may be heated to anysuitable temperature. In some examples, the battery cell is heated toand/or maintained at a temperature of about 200° C., about 250° C.,about 300° C., about 350° C., about 400° C., about 450° C., about 500°C., about 550° C., about 600° C., about 650° C., or about 700° C. Thebattery cell may be heated to and/or maintained at a temperature of atleast about 200° C., at least about 250° C., at least about 300° C., atleast about 350° C., at least about 400° C., at least about 450° C., atleast about 500° C., at least about 550° C., at least about 600° C., atleast about 650° C., or at least about 700° C. In some situations, thebattery cell is heated to between 200° C. and about 500° C., or betweenabout 300° C. and 450° C.

Electrochemical cells of the disclosure may be adapted to cycle betweencharged (or energy storage) modes and discharged modes. In someexamples, an electrochemical cell can be fully charged, partiallycharged or partially discharged, or fully discharged.

In some implementations, during a charging mode of an electrochemicalenergy storage device, electrical current received from an externalpower source (e.g., a generator or an electrical grid) may cause metalatoms in the metal positive electrode to release one or more electrons,dissolving into the electrolyte as a positively charged ion (i.e.,cation). Simultaneously, cations of the same species can migrate throughthe electrolyte, and may accept electrons at the negative electrode,causing the cations to transition to a neutral metal species, therebyadding to the mass of the negative electrode. The removal of the activemetal species from the positive electrode and the addition of the activemetal to the negative electrode stores electrochemical energy. During anenergy discharge mode, an electrical load is coupled to the electrodesand the previously added metal species in the negative electrode can bereleased from the metal negative electrode, pass through the electrolyteas ions, and alloy with the positive electrode, with the flow of ionsaccompanied by the external and matching flow of electrons through theexternal circuit/load. This electrochemically facilitated metal alloyingreaction discharges the previously stored electrochemical energy to theelectrical load.

In a charged state, the negative electrode can include negativeelectrode material and the positive electrode can include positiveelectrode material. During discharging (e.g., when the battery iscoupled to a load), the negative electrode material yields one or moreelectrons and cations of the negative electrode material. The cationsmigrate through the electrolyte to the positive electrode material andreact with the positive electrode material to form an alloy. Duringcharging, the alloy at the positive electrode disassociates to yieldcations of the negative electrode material, which migrates through theelectrolyte to the negative electrode.

In some examples, ions can migrate through an electrolyte from an anodeto a cathode, or vice versa. In some cases, ions can migrate through anelectrolyte in a push-pop fashion in which an entering ion of one typeejects an ion of the same type from the electrolyte. For example, duringdischarge, a lithium anode and a lithium chloride electrolyte cancontribute a lithium cation to a cathode by a process in which a lithiumcation formed at the anode interacts with the electrolyte to eject alithium cation from the electrolyte into the cathode. The lithium cationformed at the anode in such a case may not necessarily migrate throughthe electrolyte to the cathode. The cation can be formed at an interfacebetween the anode and the electrolyte, and accepted at an interface ofthe cathode and the electrolyte.

The present disclosure provides Type 1 and Type 2 cells, which can varybased on, and be defined by, the composition of the active components(e.g., negative electrode, electrolyte and positive electrode), andbased on the mode of operation of the cells (e.g., low voltage modeversus high voltage mode).

In an example Type 1 cell, upon discharging, cations formed at thenegative electrode can migrate into the electrolyte. Concurrently, theelectrolyte can provide a cation of the same species (e.g., the cationof the negative electrode material) to the positive electrode, which canreduce from a cation to a neutrally charged metallic species, and alloywith the positive electrode. In a discharged state, the negativeelectrode can be depleted of the negative electrode material (e.g., Na,Li, Ca, Mg). During charging, the alloy at the positive electrodedisassociates to yield cations of the negative electrode material (e.g.Na⁺, Li⁺, Ca²⁺, Mg²⁺), which migrate into the electrolyte. Theelectrolyte can then provide cations (e.g., the cation of the negativeelectrode material) to the negative electrode, which replenishes thenegative electrode to provide a cell in a charged state. A Type 1 cellcan operate in a push-pop fashion, in which the entry of a cation intothe electrolyte results in the discharge of the same cation from theelectrolyte.

In an example Type 2 cell, in a discharged state the electrolytecomprises cations of the negative electrode material (e.g., Na⁺, Li⁺,Ca²⁺, Mg²⁺), and the positive electrode comprises positive electrodematerial (e.g., Pb, Sn, Zn, Hg). During charging, a cation of thenegative electrode material from the electrolyte accepts one or moreelectrons (e.g., from a negative current collector) to form the negativeelectrode comprising the negative electrode material. In some examples,the negative electrode material wets into a foam (or porous) structureof the negative current collector. Concurrently, positive electrodematerial from the positive electrode dissolves into the electrolyte ascations of the positive electrode material (e.g., Pb²⁺, Sn²⁺, Zn²⁺,Hg²⁺). The concentration of the cations of the positive electrodematerial can vary in vertical proximity within the electrolyte (e.g. asa function of distance above the positive electrode material) based onthe atomic weight and diffusion dynamics of the cation material in theelectrolyte. In some examples, the cations of the positive electrodematerial are concentrated in the electrolyte near the positiveelectrode.

Electrochemical cells of the disclosure can include housings that may besuited for various uses and operations. A housing can include one cellor a plurality of cells. A housing can be configured to electricallycouple the electrodes to a switch, which can be connected to theexternal power source and the electrical load. The cell housing mayinclude, for example, an electrically conductive container that iselectrically coupled to a first pole of the switch and/or another cellhousing, and an electrically conductive container lid, a portion ofwhich is electrically coupled to a second pole of the switch and/oranother cell housing. The cell can be arranged within a cavity of thecontainer. A first one of the electrodes of the cell can contact and beelectrically coupled with an endwall of the container. An electricallyinsulating sheath (e.g., alumina sheath) may electrically insulateremaining portions of the cell from other portions of the container. Aconductor can electrically couple a second one of the electrodes of thebattery cell to the container lid, which can seal (e.g., hermeticallyseal) the battery cell within the cavity. The container and thecontainer lid can be electrically isolated. As an alternative, a housingdoes not include an electrically insulating sheath. In some cases, ahousing and/or container may be a battery housing and/or container. Anelectrically conductive sheath (e.g. graphite sheath) may prevent thecathode from wetting up the side walls of the container.

A battery, as used herein, can comprise a plurality of electrochemicalcells. Individual cells of the plurality can be electrically coupled toone another in series and/or in parallel and/or a combination of seriesand parallel connections. In serial connectivity, the positive terminalof a first cell is connected to a negative terminal of a second cell. Inparallel connectivity, the positive terminal of a first cell can beconnected to a positive terminal of a second cell.

Reference will now be made to the figures, wherein like numerals referto like parts throughout. It will be appreciated that the figures andfeatures therein are not necessarily drawn to scale.

With reference to FIG. 1, an electrochemical cell (A) is a unitcomprising an anode and a cathode. The cell may comprise an electrolyteand be sealed in a housing as described herein. In some cases, theelectrochemical cells can be stacked (B) to form a battery (i.e., acompilation of electrochemical cells). The cells can be arranged inparallel, in series, or both in parallel and in series (C).

Electrochemical cells of the disclosure may be capable of storing and/orreceiving input of (“taking in”) substantially large amounts of energy.In some instances, a cell is capable of storing and/or taking in about 1watt hour (Wh), about 5 Wh, 25 Wh, about 50 Wh, about 100 Wh, about 500Wh, about 1 kilo-Wh (kWh), about 1.5 kWh, about 2 kWh, about 3 kWh,about 5 kWh, about 10 kWh, about 100 kWh, about 500 kWh, about 1 MWh,about 5 MWh, about 10 MWh, about 50 MWh, or about 100 MWh. In someinstances, the battery is capable of storing and/or taking in at leastabout 1 Wh, at least about 5 Wh, at least about 25 Wh, at least about 50Wh, at least about 100 Wh, at least about 500 Wh, at least about 1 kWh,at least about 1.5 kWh, at least about 2 kWh, at least about 3 kWh, atleast about 5 kWh, at least about 10 kWh, at least about 100 kWh, atleast about 500 kWh, at least about 1 MWh, at least about 5 MWh, atleast about 10 MWh, at least about 50 MWh, or at least about 100 MWh. Acell may be capable of providing a current at a current density of atleast about 10 mA/cm², 20 mA/cm², 30 mA/cm², 40 mA/cm², 50 mA/cm², 60mA/cm², 70 mA/cm², 80 mA/cm², 90 mA/cm², 100 mA/cm², 200 mA/cm², 300mA/cm², 400 mA/cm², 500 mA/cm², 600 mA/cm², 700 mA/cm², 800 mA/cm², 900mA/cm², 1 A/cm², 2 A/cm², 3 A/cm², 4 A/cm², 5 A/cm², or 10 A/cm²; wherethe current density is determined based on the effective cross-sectionalarea of the electrolyte and where the cross-sectional area is the areathat is orthogonal to the net flow direction of ions through theelectrolyte during charge or discharge processes.

A compilation or array of cells (i.e., battery) can include any suitablenumber of cells, such as at least about 2, at least about 5, at leastabout 10, at least about 50, at least about 100, at least about 500, atleast about 1000, at least about 5000, at least about 10000, and thelike. In some examples, a battery includes 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600,700, 800, 900, 1000, 2000, 5000, 10,000, 20,000, 50,000, 100,000,500,000, or 1,000,000 cells.

Batteries of the disclosure may be capable of storing and/or taking in asubstantially large amount of energy for use with a power grid (i.e., agrid-scale battery) or other loads or uses. In some instances, a batteryis capable of storing and/or taking in about 5 kWh, 25 kWh, about 50kWh, about 100 kWh, about 500 kWh, about 1 megawatt hour (MWh), about1.5 MWh, about 2 MWh, about 3 MWh, about 5 MWh, or about 10 MWh. In someinstances, the battery is capable of storing and/or taking in at leastabout 1 kWh, at least about 5 kWh, at least about 25 kWh, at least about50 kWh, at least about 100 kWh, at least about 500 kWh, at least about 1MWh, at least about 1.5 MWh, at least about 2 MWh, at least about 3 MWh,or at least about 5 MWh, or at least about 10 MWh.

In some instances, the cells and cell housings are stackable. Anysuitable number of cells can be stacked. Cells can be stackedside-by-side, on top of each other, or both. In some instances, at leastabout 10, 50, 100, or 500 cells are stacked. In some cases, a stack ofabout 1000 cells is capable of storing and/or taking in at least 50 kWhof energy. A first stack of cells (e.g., 10 cells) can be electricallyconnected to a second stack of cells (e.g., another 10 cells) toincrease the number of cells in electrical communication (e.g., 20 inthis instance).

An electrochemical energy storage device can include one or moreindividual electrochemical cells. An electrochemical cell can be housedin a container, which can include a container lid. The device caninclude at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 100,200, 300, 400, 500, 1000, 10,000, 20,000, or 50,000 cells. The containerlid may utilize, for example, a gasket (e.g., annular dielectric gasket)to electrically isolate the container from the container lid. Such agasket may be constructed from a relatively hard electrically insulatingmaterial, such as, for example, glass, silicon oxide, aluminum oxide,boron nitride, aluminum nitride, or other oxides comprising of lithiumoxide, calcium oxide, barium oxide, yttrium oxide, silicon oxide,aluminum oxide, or lithium nitride. The gasket may be subject torelatively high compressive forces (e.g., greater than 10,000 psi)between the container lid and the container in order to provide a sealin addition to electrical isolation. In order to subject the dielectricgasket to such high compressive forces, the fasteners may haverelatively large diameters and may be closely spaced together. Suchlarge diameter fasteners may be expensive and, thus, may significantlyincrease the cost to build a relatively large diameter container. Inaddition, as the diameter of the dielectric gasket is increased toaccommodate a large diameter container, the gasket may become more andmore fragile and difficult to maneuver.

FIG. 2 schematically illustrates a battery that comprises anelectrically conductive housing 201 and a conductor 202 in electricalcommunication with a current collector 203. The conductor can beelectrically isolated from the housing and can protrude through thehousing through an aperture in the housing such that the conductor of afirst cell contacts the housing of a second cell when the first andsecond cells are stacked.

In some cases, a cell comprises a negative current collector, a negativeelectrode, an electrolyte, a positive electrode and a positive currentcollector. The negative electrode can be part of the negative currentcollector. As an alternative, the negative electrode is separate from,but otherwise kept in electrical communication with, the negativecurrent collector. The positive electrode can be part of the positivecurrent collector. As an alternative, the positive electrode can beseparate from, but otherwise kept in electrical communication with, thepositive current collector.

A cell housing can comprise an electrically conductive container and aconductor in electrical communication with a current collector. Theconductor may protrude through the housing through an aperture in thecontainer and may be electrically isolated from the container. Theconductor of a first housing may contact the container of a secondhousing when the first and second housings are stacked.

In some instances, the area of the aperture through which the conductorprotrudes from the housing and/or container is small relative to thearea of the housing and/or container. In some cases, the ratio of thearea of the aperture to the area of the housing is about 0.001, about0.005, about 0.01, about 0.05, about 0.1, about 0.15, or about 0.2. Insome cases, the ratio of the area of the aperture to the area of thehousing is less than or equal to 0.001, less than or equal to 0.005,less than or equal to 0.01, less than or equal to 0.05, less than orequal to 0.1, less than or equal to 0.15, or less than or equal to 0.2.

A cell can comprise an electrically conductive housing and a conductorin electrical communication with a current collector. The conductorprotrudes through the housing through an aperture in the housing and maybe electrically isolated from the housing. The ratio of the area of theaperture to the area of the housing may be less than about 0.1.

A cell housing can comprise an electrically conductive container and aconductor in electrical communication with a current collector. Theconductor protrudes through the container through an aperture in thecontainer and is electrically isolated from the container. The ratio ofthe area of the aperture to the area of the container may be less than0.1. The housing can be capable of enclosing a cell that is capable ofstoring and/or taking in less than 100 Wh of energy, about 100 Wh ofenergy, or more than 100 Wh of energy.

FIG. 3 is a cross-sectional side view of an electrochemical cell orbattery 300 comprising a housing 301, a conductive feed-through (i.e.,conductor, such as a conductor rod) 302 that passes through an aperturein the housing and is in electronic communication with a liquid metalnegative electrode 303, a liquid metal positive electrode 305, and aliquid metal electrolyte between the electrodes 303, 305. The conductor302 may be electrically isolated from the housing 301 (e.g., usingelectrically insulating gaskets). The negative electrode 303 may be afoam that behaves like a sponge, and is “soaked” in liquid metal. Thenegative liquid metal electrode 303 is in contact with the molten saltelectrolyte 304, which is in contact with the positive liquid metalelectrode 305. The positive liquid metal electrode 305 can contact thehousing 301 along the side walls and/or along the bottom end wall of thehousing.

The foam can be porous. The foam can include pores that are sized topermit ions to flow through the pores. The foam can be sized to permitthe liquid metal to flow through the foam.

The housing 301 can be constructed from an electrically conductivematerial such as, for example, steel, iron, stainless steel, graphite,nickel, nickel based alloys, titanium, aluminum, molybdenum, ortungsten. The housing may also comprise a thinner lining component of aseparate metal or electrically insulating coating, such as, for example,a steel housing with a graphite lining, a steel housing with a boron orboron nitride coating, or titanium coating. The coating can exhibitfavorable properties and functions, including surfaces that areanti-wetting to the positive electrode liquid metal. In some cases, thelining (e.g., graphite lining) may be dried by heating above roomtemperature in air or dried in a vacuum oven before or after beingplaced inside the cell housing. Drying or heating the lining may removemoisture from the lining prior to adding the electrolyte, positiveelectrode, or negative electrode to the cell housing.

The housing 301 may include a thermally and/or electrically insulatingsheath 306. In this configuration, the negative electrode 303 may extendlaterally between the side walls of the housing 301 defined by thesheath without being electrically connected (i.e., shorted) to thepositive electrode 305. Alternatively, the negative electrode 303 mayextend laterally between a first negative electrode end 303 a and asecond negative electrode end 303 b. When the sheath 306 is notprovided, the negative electrode 303 may have a diameter (or othercharacteristic dimension, illustrated in FIG. 3 as the distance from 303a to 303 b) that is less than the diameter (or other characteristicdimension such as width for a cuboid container, illustrated in FIG. 3 asthe distance D) of the cavity defined by the housing 301.

The sheath 306 can be constructed from a thermally insulating and/orelectrically insulating material such as, for example, alumina, titania,silica, magnesia, boron nitride, or a mixed oxide including calciumoxide, aluminum oxide, silicon oxide, lithium oxide, magnesium oxide,etc. As shown in FIG. 3, the sheath 306 has an annular, square, orrectangular cross-sectional geometry that can extend laterally between afirst sheath end 306 a and a second sheath end 306 b. The sheath may bedimensioned (illustrated in FIG. 3 as the distance from 306 a to 306 b)such that the sheath is in contact and pressed up against the side wallsof the cavity defined by the housing cavity 301. As an alternative, thesheath can be used to prevent corrosion of the container and/or preventwetting of the cathode material up the side wall, and may be constructedout of an electronically conductive material, such as steel, stainlesssteel, tungsten, molybdenum, nickel, nickel based alloys, graphite, ortitanium. The sheath may be very thin and could be a coating. Thecoating can cover just the inside of the walls, and/or, can also coverthe bottom of the inside of the container. In some cases, the sheath(e.g., graphite sheath) may be dried by heating above room temperaturein air or dried in a vacuum oven before or after being placed inside thecell housing. Drying or heating the lining may remove moisture from thelining prior to adding the electrolyte, positive electrode, or negativeelectrode to the cell housing.

Instead of a sheath, the cell may comprise an electrically conductivecrucible or coating that lines the side walls and bottom inner surfaceof the cell housing, referred to as a cell housing liner, preventingdirect contact of the positive electrode with the cell housing. The cellhousing liner may prevent wetting of the positive electrode between thecell housing and the cell housing liner or sheath and may prevent directcontact of the positive electrode on the bottom surface of the cellhousing. The sheath may be very thin and can be a coating. The coatingcan cover just the inside of the walls, and/or, can also cover thebottom of the inside of the container. The sheath may not fit perfectlywith the housing 301 which may hinder the flow of current between thecell lining and the cell housing. To ensure adequate electronicconduction between the cell housing and the cell lining, a liquid ofmetal that has a low melting point (i.e. Pb, Sn, Bi) can be used toprovide a strong electrical connection between the sheath/coating andthe cell housing. This layer can allow for easier fabrication andassembly of the cell.

The housing 301 can also include a first (e.g., negative) currentcollector 307 and a second (e.g., positive) current collector 308. Thenegative current collector 307 may be constructed from an electricallyconductive material such as, for example, nickel-iron (Ni—Fe) foam,perforated steel disk, sheets of corrugated steel, sheets of expandedmetal mesh, etc. The negative current collector 307 may be configured asa plate that can extend laterally between a first collector end 307 aand a second collector end 307 b. The negative current collector 307 mayhave a collector diameter that is less than or equal to the diameter ofthe cavity defined by the housing 301. In some cases, the negativecurrent collector 307 may have a collector diameter (or othercharacteristic dimension, illustrated in FIG. 3 as the distance from 307a to 307 b) that is less than, equal to, or more than the diameter (orother characteristic dimension, illustrated in FIG. 3 as the distancefrom 303 a to 303 b) of the negative electrode 303. The positive currentcollector 308 may be configured as part of the housing 301; for example,the bottom end wall of the housing may be configured as the positivecurrent collector 308, as illustrated in FIG. 3. Alternatively, thecurrent collector may be discrete from the battery housing and may beelectrically connected to the battery housing. In some cases, thepositive current collector may not be electrically connected to thebattery housing. The present invention is not limited to any particularconfigurations of the negative and/or positive current collectorconfigurations.

In some cases, a cell can include one or more alloyed products that areliquid, semi-liquid (or semi-solid), or solid. The alloyed products canbe immiscible with the negative electrode, positive electrode and/orelectrolyte. The alloyed products can form from electrochemicalprocesses during charging or discharging of a cell.

An alloyed product can include an element constituent of a negativeelectrode, positive electrode and/or electrolyte. An alloyed product canhave a different density than the negative electrode, positive electrodeor electrolyte, or a density that is similar or substantially the same.The location of the alloyed product can be a function of the density ofthe alloyed product compared to the densities of the negative electrode,electrolyte and positive electrode. The alloyed product can be situatedin the negative electrode, positive electrode, or electrolyte, or at alocation (e.g., interface) between the negative electrode and theelectrolyte or between the positive electrode and the electrolyte. In anexample, an alloyed product is an intermetallic between the positiveelectrode and the electrolyte (see FIG. 4). In other examples, thealloyed product can be at other locations within the cell and be formedof a material of different stoichiometries/compositions, depending onthe chemistry, temperature, and/or charge state of the cell.

The negative electrode 303 can be contained within the negative currentcollector (e.g., foam) 307. In this configuration, the electrolyte layercomes up in contact with the bottom and sides of the foam 307, and themetal contained in the foam (i.e., the negative electrode material) canbe held away from the sidewalls of the housing 301, thus allowing thecell to run without the insulating sheath 306. In some cases, a graphitesheath may be used to prevent the positive electrode from wetting upalong the side walls, which can prevent shorting of the cell.

Current may be distributed substantially evenly across a positive and/ornegative liquid metal electrode in contact with an electrolyte along asurface (i.e., the current flowing across the surface may be uniformsuch that the current flowing through any portion of the surface doesnot substantially deviate from an average current density). In someexamples, the maximum density of current flowing across an area of thesurface is less than about 105%, less than about 115%, less than about125%, less than about 150%, less than about 175%, less than about 200%,less than about 250%, or less than about 300% of the average density ofcurrent flowing across the surface. In some examples, the minimumdensity of current flowing across an area of the surface is greater thanabout 50%, greater than about 60%, greater than about 70%, greater thanabout 80%, greater than about 90%, or greater than about 95% of theaverage density of current flowing across the surface.

The housing may include a container and a container lid as describedelsewhere herein. The container and container lid may be connectedmechanically and isolated electrically (e.g., using electricallyinsulating gaskets, fasteners with electrically insulating sleevesand/or electrically insulating washers constructed from a dielectricsuch as, for example, mica or vermiculite). In some examples, theelectrochemical cell or battery 300 may comprise two or more conductorspassing through one or more apertures and in electrical communicationwith the liquid metal negative electrode 303. In some instances, aseparator structure (not shown) may be arranged within the electrolyte304 between the liquid negative electrode 303 and the (liquid) positiveelectrode 305.

Viewed from a top or bottom direction, as indicated respectively by “TOPVIEW” and “BOTTOM VIEW” in FIG. 3, the cross-sectional geometry of thecell or battery 300 can be circular, elliptical, square, rectangular,polygonal, curved, symmetric, asymmetric or any other compound shapebased on design requirements for the battery. In one example, the cellor battery 300 is axially symmetric with a circular cross-section.Components of cell or battery 300 (e.g., component in FIG. 3) may bearranged within the cell or battery in an axially symmetric fashion. Insome cases, one or more components may be arranged asymmetrically, suchas, for example, off the center of the axis 309.

The combined volume of positive and negative electrode material may beabout 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about80%, about 90%, or about 95% of the volume of the battery (e.g., asdefined by the outer-most housing of the battery, such as a shippingcontainer). In some cases, the combined volume of anode and cathodematerial is at least 20%, at least 30%, at least 40%, at least about50%, at least about 60%, at least about 70%, at least about 80%, atleast about 90%, or at least about 95% of the volume of the battery. Thecombined volume of the positive and negative electrodes material mayexpand or contract during operation due to the expansion or contractionof the positive or negative electrode. In an example, during discharge,the volume of the negative electrode (anode during discharge) may bereduced due to transfer of the negative electrode material to thepositive electrode (cathode during discharge), wherein the volume of thepositive electrode is increased (e.g., as a result of an alloyingreaction). The volume reduction of the negative electrode may or may notequal the volume increase of the positive electrode. The positive andnegative electrode materials may react with each other to form a solidor semi-solid mutual reaction compound (also “mutual reaction product”herein), which may have a density that is the same, lower, or higherthan the densities of the positive and/or negative electrode materials.Although the mass of material in the electrochemical cell or battery 300may be constant, one, two or more phases (e.g., liquid or solid) may bepresent, and each such phase may comprise a certain material composition(e.g., an alkali metal may be present in the materials and phases of thecell at varying concentrations: a liquid metal negative electrode maycontain a high concentration of an alkali metal, a liquid metal positiveelectrode may contain an alloy of the alkali metal and the concentrationof the alkali metal may vary during operation, and a mutual reactionproduct of the positive and negative liquid metal electrodes may containthe alkali metal at a fixed or variable stoichiometry). The phasesand/or materials may have different densities. As material istransferred between the phases and/or materials of the electrodes, achange in combined electrode volume may result.

FIG. 4 is a cross-sectional side view of an electrochemical cell orbattery 400 with an intermetallic layer 410. The intermetallic layer 410can include a mutual reaction compound that may be formed duringdischarging at an interface between a positive liquid metal electrode(liquid metal cathode in this configuration) 405 and a liquid metalelectrolyte 404. The mutual reaction compound (or product) can be solidor semi-solid. The intermetallic layer 410 can form at the interfacebetween the liquid metal cathode 405 and the liquid metal electrolyte404. In some cases, the intermetallic layer 410 may exhibit liquidproperties (e.g., the intermetallic may be semi-solid, or it may be of ahigher viscosity or density than one or more adjacent phases/materials).

In some cases, a negative liquid metal electrode 403 includes lithium,sodium, potassium, magnesium, and/or calcium, the positive liquid metalelectrode 405 includes lead, antimony, tin, tellurium and/or bismuth.The intermetallic layer 410 can include any suitable compound such asmagnesium antimonide (Mg₃Sb₂), calcium antimonide (Ca₃Sb₂), lithiumantimonide (Li₃Sb), lithium bismuthide (Li₃Bi), sodium antimonide(Na₃Sb) or compounds that contain two or more of K, Li, Na, Pb, Bi, Sb,Te, Sn and the like.

In an example, a negative liquid metal electrode 403 includes magnesium(Mg), the positive liquid metal electrode 405 includes antimony (Sb),and the intermetallic layer 410 includes Mg and Sb (Mg_(x)Sb, where ‘x’is a number greater than zero), such as, for example, magnesiumantimonide (Mg₃Sb₂). Cells with a Mg∥Sb chemistry may contain magnesiumions within the electrolyte as well as other salts (e.g., MgCl₂, NaCl,KCl, or a combination thereof). In a discharged state, the cell isdeficient in Mg in the negative electrode and the positive electrodecomprises an alloy of Mg—Sb, and during charging, Mg is supplied fromthe positive electrode, passes through the electrolyte as a positiveion, and deposits onto the negative current collector as Mg. In someexamples, the cell has an operating temperature of at least about 550°C., 600° C., 650° C., 700° C., or 750° C., and in some cases between650° C. and 750° C. In a charged state, all or substantially all thecomponents of the cell are in a liquid state. Alternative chemistriesexist, including Ca-Mg∥Bi comprising a calcium halide constituent in theelectrolyte (i.e. CaCl₂, KCl, LiCl, or combinations thereof) andoperating above 500° C., Li∥Pb-Sb cells comprising a lithium halideelectrolyte (i.e. LiF, LiCl, LiBr, or combinations thereof) andoperating between 350° C. and 550° C., and Na∥Pb cells comprising asodium halide as part of the electrolyte (i.e. NaCl, NaF, LiCl, LiF,LiBr, KCl, KBr, or combinations thereof) and operating above 300° C. Insome cases, the product of the discharge reaction may be anintermetallic compound (i.e. Mg₃Sb₂ for the Mg∥Sb cell chemistry, Li₃Sbfor the Li∥Pb-Sb chemistry, or Ca₃Bi₂ for the Ca—Mg∥Bi chemistry) wherethe intermetallic layer may develop as a distinct solid phase by growingand expanding horizontally along a direction x and/or growing orexpanding vertically along a direction y at the interface between thepositive electrode and the electrolyte. The solid intermetallic layermay develop by growing and expanding horizontally along a direction x.The expansion or growth may be axially symmetrical or asymmetrical withrespect to an axis of symmetry 409 located at the center of the cell orbattery 400. Alternatively, the solid intermetallic layer may developand expand starting from one or more locations (also “nucleation sites”herein) along a surface parallel to the direction x (i.e., the interfacebetween the liquid metal cathode and the liquid metal electrolyte). Thenucleation sites may be located in a predetermined pattern along thesurface; alternatively, the location of the nucleation sites may bestochastic (random), or determined by natural or induced defects at theinterface between the liquid metal cathode and the liquid metalelectrolyte, or elsewhere within the cell or battery 400. In someexamples, the solid intermetallic layer may not grow and expandhorizontally. For example, the solid intermetallic layer may form evenlyacross the interface.

The solid intermetallic layer may begin developing at or near a verticallocation corresponding to the location of the upper surface of theliquid metal cathode at the commencement of discharging (i.e., theinterface between the liquid metal cathode and the liquid metalelectrolyte at the commencement of discharging), and may then grow in adownward direction y. Thus, the solid intermetallic layer may have anupper interface or surface 410 a and a lower interface or surface 410 b.The upper interface 410 a may remain in an approximately fixed locationalong the axis 409, while the lower interface 410 b moves in a downwarddirection during discharge. In some cases, the solid intermetallic layermay grow and/or deform in the downward direction (i.e., intermetallicmaterial is added to the layer from the downward direction opposite tovector y). Material buildup along the interface 410 b may cause pressureto build up from below. The pressure may exert a force on theintermetallic layer. The pressure may be hydraulic pressure from theliquid metal cathode 405. In some cases, the pressure may be due tomaterial stresses in the intermetallic layer 410. This may, for example,cause the intermetallic layer 410 to bulge or bow upward. In some cases,the liquid metal cathode may break through the intermetallic layer andsome liquid metal cathode material may eject into the liquid metalelectrolyte past the upper surface of the intermetallic layer, formingfingers or dendritic outgrowths. The intermetallic layer may bepartially distorted, and may be ruptured or cracked in one or morelocations along the interface 410 a.

In some cases, a combination of horizontal and downward growth mayoccur. For example, a layer having a thickness t may develop in adownward direction along the central axis, and expand horizontallyduring discharge at a thickness of less than t, about t, or larger thant. The thickness t may also change as a function of discharge ordischarge time. The morphology of the interfaces 410 a, 410 b may not beas uniform as shown in FIG. 4. For example, the interfaces may be lumpy,jagged, uneven, spongy or have offshoots, fingers or dendriticcharacteristics. For example, the interface 410 a can be undulating.Depending on the lateral extent of the intermetallic layer 410 withrespect to the dimension of the cavity defined by the side walls ofsheath 406 or housing 401 and/or the morphology of the intermetalliclayer 410, one or more interfaces between the liquid metal electrolyte404 and the liquid metal cathode 405 may exist. The interfaces mayprovide a means for reduction reactions to proceed at the liquid metalcathode. The solid intermetallic layer may grow by the addition ofmaterial formed at or near the interfaces.

During discharge, the cathode may comprise the liquid metal cathode 405,and the solid intermetallic layer 410 is formed adjacent to the cathode.As previously described, material can be transferred to the cathodeduring discharge such that the mass of the cathode grows. The cathodevolume may expand as a result of the material addition. The volumeexpansion may be affected by the alloying reaction. For example, thecathode volume increase after alloying may be about 30% less thanexpected from adding together the volume of material added to thecathode and the material originally present in the cathode. In somecases, the densities of the intermetallic layer 410 and the liquid metalcathode 405 may be about the same. Alternatively, the density of theintermetallic layer may be higher or lower than the density of theliquid metal cathode 405. For example, the density of the intermetalliclayer may be a function of the phase structure of the solid formed. Asthe cathode volume increases during discharging, individually, theintermetallic layer 410 may grow, but the liquid metal cathode 405 maybe consumed. The intermetallic layer 410 may grow at the expense of theliquid metal cathode 405. Alternatively, the volumes of both theintermetallic layer 410 and the liquid metal cathode 405 may increase,but the increase in volume of the liquid metal cathode 405 is less thanit would otherwise be in the absence of an intermetallic layer. In someexamples, the alloy in the liquid metal cathode 405, and the alloy inthe intermetallic layer 410 may be formed independently at theinterfaces between the liquid metal electrolyte and the liquid metalcathode. Alternatively, the formation of the intermetallic layer 410 mayconsume alloy first formed in the liquid metal cathode 405. Theexpansion of the liquid metal cathode 405 confined by an intermetalliclayer 410, and the sheath 406 or housing 401 may lead to hydraulicpressure buildup in the liquid metal cathode 405.

With continued reference to FIG. 4, the intermetallic 410 can be locatedbetween the liquid metal electrolyte 404 and the liquid metal cathode405. During normal operation, the cell or battery 400 can be oriented inthe direction shown in FIG. 4, such that any gravitational pullaffecting the cell is oriented downward in the direction of the vectory.A hydrostatic pressure from the liquid metal electrolyte 404 may exert adownward force (in the direction of y) on the intermetallic layer 410.This force may remain constant during discharge, as the mass of theliquid metal electrolyte may not change. The upper interface 410 a ofthe intermetallic layer may be stationary. As the intermetallic layer410 grows, a hydraulic pressure may build up in the liquid metal cathode405, and may exert an upward force (in the opposite direction from y) onthe intermetallic layer 410.

In another aspect of the present disclosure, an energy storage devicecomprises at least one liquid metal electrode. The energy storage devicecan have a high energy storage capacity and a fast response time. Theliquid metal electrode can be an anode or a cathode of the energystorage device. In some embodiments, the energy storage devicescomprises a liquid metal anode (e.g., lithium, sodium, calcium, and/orpotassium) and a liquid metal cathode (e.g., antinomy, bismuth,tellurium, tin, and/or lead). The energy storage device can alsocomprise a liquid electrolyte. In some embodiments, the reactions thatoccur at the electrode and liquid metal electrode interfaces areextremely facile, permitting high current density operation with minimalelectrode overpotentials and extremely fast response times.

The energy storage capacity can be any suitably large value (e.g.,suitable for grid-scale energy storage), including about 1 kWh, about 10kWh, about 20 kWh, about 30 kWh, about 100 kWh, about 500 kWh, about 1MWh, about 5 MWh, about 10 MWh, about 50 MWh, about 100 MWh, and thelike. In some embodiments, the energy storage capacity is at least about1 kWh, at least about 10 kWh, at least about 20 kWh, at least about 30kWh, at least about 100 kWh, at least about 500 kWh, at least about 1MWh, at least about 5 MWh, at least about 10 MWh, at least about 50 MWh,at least about 100 MWh and the like.

The response time can be any suitable value (e.g., suitable forresponding to disturbances in the power grid). In some instances, theresponse time is about 100 milliseconds (ms), about 50 ms, about 10 ms,about 1 ms, and the like. In some cases, the response time is at mostabout 100 milliseconds (ms), at most about 50 ms, at most about 10 ms,at most about 1 ms, and the like.

In some embodiments, the liquid metal electrode comprises an alkaliearth metal, a metalloid, or combinations thereof. In some embodiments,the liquid metal electrode comprises lithium, sodium, potassium,magnesium, calcium, or any combination thereof. In some cases, theliquid metal electrode comprises antimony, lead, tin, tellurium, bismuthor combinations thereof.

In some embodiments, the device is comprised in an array of energystorage devices as part of an energy storage system. The device can bean energy storage cell, and the energy storage system comprises aplurality of energy storage cells.

In another aspect of the present disclosure, an energy storage devicecomprises at least one liquid metal electrode stored in a container at atemperature greater than or equal to about 250° C. The energy storagedevice can have a high energy storage capacity and the container canhave a surface area-to-volume ratio that is less than or equal to about10 m⁻¹.

The energy storage capacity can be any suitably large value (e.g.,suitable for grid-scale energy storage), including about 1 kWh, about 10kWh, about 20 kWh, about 30 kWh, about 100 kWh, about 500 kWh, about 1MWh, about 5 MWh, about 10 MWh, about 50 MWh, about 100 MWh, and thelike. In some embodiments, the energy storage capacity is at least about1 kWh, at least about 10 kWh, at least about 20 kWh, at least about 30kWh, at least about 100 kWh, at least about 500 kWh, at least about 1MWh, at least about 5 MWh, at least about 10 MWh, at least about 50 MWh,at least about 100 MWh and the like.

In some embodiments, the surface area-to-volume ratio is about 100 m⁻¹,about 50 m⁻¹, about 10 m⁻¹, about 1 m⁻¹, about 0.5 m⁻¹, about 0.1 m⁻¹,about 0.01 m⁻¹, or about 0.001 m⁻¹. In some cases, the surfacearea-to-volume ratio is less than about 100 m⁻¹, less than about 50 m⁻¹,less than about 10 m⁻¹, less than about 1 m⁻¹, less than about 0.5 m⁻¹,less than about 0.1 m⁻¹, less than about 0.01 m⁻¹, or less than about0.001 m⁻¹.

The temperature can be any suitable temperature (e.g., for maintainingthe electrodes in a molten state). In some embodiments, the at least oneliquid metal electrode is stored in the container at a temperaturegreater than or equal to about 250° C., greater than or equal to about400° C., greater than or equal to about 450° C. greater than or equal toabout 500° C. or greater than or equal to about 550° C.

In another aspect of the present disclosure, an energy storage devicecomprises at least one liquid metal electrode and the energy storagedevice maintains at least 90% of its energy storage capacity after 100charge/discharge cycles.

In some cases, the energy storage device has an energy storage capacityof at least about 1 kWh. In some embodiments, the energy storage devicehas an energy storage capacity of at least about 2 kWh, 3 kWh, 4 kWh, 5kWh, 6 kWh, 7 kWh, 8 kWh, 9 kWh, 10 kWh, 20 kWh, 30 kWh, 100 kWh, 200kWh, 300 kWh, 400 kWh, 500 kWh, 1 MWh, 5 MWh, or 10 MWh.

In some embodiments, the energy storage device maintains at least 90%,95%, 96%, 97%, 98%, or 99% of its energy storage capacity after 100,200, 300, 400, 500, or 1000, 3000, 5000, 10,000 charge/discharge cycles.

In some embodiments, an energy storage device comprises at least oneliquid metal electrode, where the device is transportable on a vehicleand has an energy storage capacity of at least about 1 kWh. The energystorage device is transportable with at least any two of an anode,cathode and electrolyte of the energy storage device in solid state.

An energy storage device can be transported if it has less than acertain weight. In some embodiments, the energy storage device has aweight of about 10 kg, 100 kg, 500 kg, 1,000 kg, 2,000 kg, 3,000 kg,4,000 kg, 5,000 kg, 10,000 kg, or 50,000 kg. In some embodiments, anindividual cell of the energy storage device has a weight of about 0.1kg, 0.5 kg, 1 kg, 2 kg, 3 kg, 4 kg, 5 kg, 10 kg, 100 kg, 1,000 kg, or10,000 kg. In some embodiments, the energy storage device has a weightof at least about 10 kg, 100 kg, 500 kg, 1,000 kg, 2,000 kg, 3,000 kg,4,000 kg, 5,000 kg, 10,000 kg, or 50,000 kg. In some embodiments, anindividual cell of the energy storage device has a weight of at leastabout 0.1 kg, 0.5 kg, 1 kg, 2 kg, 3 kg, 4 kg, 5 kg, 10 kg, 100 kg, 1,000kg, or 10,000 kg.

In some embodiments, an energy storage device comprises a containercontaining one or more cells, an individual cell of the one or morecells containing at least one liquid metal electrode, where a rate ofheat generation in the cell during charge/discharge is about equal to arate of heat loss from the cell.

The rate of heat generation can be any suitable value compared to therate of heat loss from the cell (e.g., such that the battery isself-heating and/or maintains a constant temperature). In some cases,the ratio of the rate of heat generation to the rate of heat loss fromthe cell is about 50%, about 75%, about 80%, about 85%, about 90%, about100%, about 110%, about 120%, or about 150%. In some instances, theratio of the rate of heat generation to the rate of heat loss from thecell is at least about 50%, at least about 75%, at least about 80%, atleast about 85%, at least about 90%, at least about 100%, at least about110%, at least about 120%, or at least about 150%. In some instances,the ratio of the rate of heat generation to the rate of heat loss fromthe cell is at most about 50%, at most about 75%, at most about 80%, atmost about 85%, at most about 90%, at most about 100%, at most about110%, at most about 120%, or at most about 150%.

In another aspect of the present disclosure, a separator-less energystorage device comprises a container with at least one liquid metalelectrode, where the container has a surface area-to-volume ratio thatis less than or equal to about 100 m⁻¹, and the separator-less energystorage device has (i) a response time less than or equal to about 100milliseconds (ms), and/or (ii) an energy storage capacity of at leastabout 1 kWh. In some embodiments, the separator-less energy storagedevices comprises (i) and (ii). In some embodiments, the separator-lessenergy storage device does not include a separator.

The energy storage capacity can be any suitably large value (e.g.,suitable for grid-scale energy storage), including about 1 kWh, about 10kWh, about 20 kWh, about 30 kWh, about 100 kWh, about 500 kWh, about 1MWh, about 5 MWh, about 10 MWh, about 50 MWh, about 100 MWh, and thelike. In some embodiments, the energy storage capacity is at least about1 kWh, at least about 10 kWh, at least about 20 kWh, at least about 30kWh, at least about 100 kWh, at least about 500 kWh, at least about 1MWh, at least about 5 MWh, at least about 10 MWh, at least about 50 MWh,at least about 100 MWh, and the like.

The response time can be any suitable value (e.g., suitable forresponding to disturbances in the power grid). In some instances, theresponse time is about 100 milliseconds (ms), about 50 ms, about 10 ms,about 1 ms, and the like. In some cases, the response time is at mostabout 100 milliseconds (ms), at most about 50 ms, at most about 10 ms,at most about 1 ms, and the like.

In some embodiments, the surface area-to-volume ratio is about 100 m⁻¹,about 50 m⁻¹, about 10 m⁻¹, about 1 m⁻¹, about 0.5 m⁻¹, about 0.1 m⁻¹,about 0.01 m⁻¹, or about 0.001 m⁻¹. In some cases, the surfacearea-to-volume ratio is less than about 100 m⁻¹, less than about 50 m⁻¹,less than about 10 m⁻¹, less than about 1 m⁻¹, less than about 0.5 m⁻¹,less than about 0.1 m⁻¹, less than about 0.01 m⁻¹, or less than about0.001 m⁻¹.

In another aspect of the present disclosure, a method for forming anenergy storage device comprises shipping a container comprising anenergy storage material in solid state to a destination location, and atthe destination location supplying energy to the energy storage materialto form at least one of a liquid metal anode, liquid metal cathode, andliquid electrolyte, thereby forming the energy storage device.

In some instances, the energy storage material is not mixed duringshipping. In some cases, the energy storage device does not include aseparator. In some embodiments, during shipping, the energy storagematerial comprises at least one of a solid state anode, solid statecathode and solid state electrolyte.

In another aspect of the present disclosure, an energy storage systemcomprises: (a) a container comprising one or more energy storage cells,where an individual energy storage cell of the one or more energystorage cells comprises an energy storage material comprising at leastone liquid metal electrode; and (b) a control system comprising aprocessor with machine-executable code for monitoring at least onetemperature of the one or more energy storage cells and/or thecontainer. The processor can regulate the flow of electrical energy intoat least a subset of the one or more energy storage cells such that theenergy storage material undergoes sustained self-heating duringcharge/discharge. In some embodiments, the container comprises aplurality of energy storage cells.

In some embodiments, the processor regulates one or more processparameters of the individual energy storage cell such that a rate ofheat dissipation from the individual energy storage cell duringcharge/discharge is greater than a rate of heat loss from the individualenergy storage cell. In some embodiments, at least one liquid metalelectrode is stored in the container at a temperature greater than orequal to about 250° C., greater than or equal to about 300° C., greaterthan or equal to about 350° C., greater than or equal to about 400° C.,greater than or equal to about 450° C. greater than or equal to about500° C. or greater than or equal to about 550° C.

Pressure Relief Mechanism for Cathode (Riser Pipes)

An aspect of the disclosure relates to pressure relief mechanisms forelectrochemical cells or batteries. The pressure relief mechanisms canbe applied, for example, in liquid metal batteries described herein.Examples include application of the pressure relief mechanisms topositive battery electrodes in liquid metal batteries (e.g., forpressure relief during battery discharging, when the positive batteryelectrode functions as a cathode). The pressure relief mechanisms may beutilized to improve performance (e.g., charge cycling), longevity and/orto prevent battery failure. In other examples, pressure reliefmechanisms and structures can be applied in alternative systems, suchas, for example, in any energy storage device or energy transformationdevice with a liquid component which may expand and/or contract duringoperation. Operation may include charging, discharging, heating, coolingor any other change in state of the device.

In an illustrative example, pressure relief mechanisms and structuresare provided for a positive electrode, such as the positive liquid metalelectrode 405 in FIG. 4. The positive liquid metal electrode 405 mayexperience an expansive pressure force during discharging. Duringdischarging, the positive liquid metal electrode can function as acathode, and the negative liquid metal electrode 403 can function as ananode. If the liquid cathode cannot freely expand as material istransferred from the anode during discharge (e.g., due to the formationof the solid layer 410 atop the liquid cathode), internal pressure canbuild. This can result in undesirable morphologies (such as bowingdescribed herein) and/or sudden, uncontrolled pressure-induced puncturesor cracks that can inhibit cell operability.

Pressure relief mechanisms disclosed herein provide one or moreunobstructed physical spaces (also “chambers” herein) where the liquidcathode can freely expand and contract during cycling, thus relievingpressure. Thus, the disclosure provides a mechanism for reversiblyrelieving internal fluid pressure.

FIG. 5 is a cross-sectional side view of an electrochemical cell orbattery 500 with a pressure relief structure 511. In an example, thebattery cell 500 can have an axially symmetric, circular cross-sectionwhen viewed from above (“top view” in FIG. 5). The housing 501 can haveconcentric walls 511 a, 511 b. A first chamber or cavity can include anegative liquid metal electrode 503, a negative current collector 507, aliquid metal electrolyte 504, a positive liquid metal electrode 505 anda positive current collector 508. During discharge, a solidintermetallic layer 510 may form, as described elsewhere herein. Thepressure relief structure 511 forms a second chamber. The walls of thefirst and second chambers can form the concentric walls of the housing501 which may include a container, as described elsewhere herein. Thus,the pressure relief structure 511 is provided in the annular chamber(also referred to as “riser pipe” herein) defined by the concentricwalls. In some cases, the concentric walls of the housing may beintegrally formed. Alternatively, the concentric walls may be formedseparately and mechanically joined, e.g., by welding. The housing and/orthe walls can be formed of any materials for housings/containersdescribed herein.

During discharge, the negative liquid metal electrode 503 can be ananode and the positive liquid metal electrode 505 can be a cathode. Theintermetallic layer 510 includes an upper interface 510 a and a lowerinterface 510 b. As the lower interface 510 b of the intermetallic layer510 moves in a downward direction indicated by arrows 512, the liquidmaterial of the cathode 505 is compressed. When pressure builds due toactive electrochemistry in the first chamber space, the cathode materialcan rise between the walls 511 a, 511 b of the pressure relief structure511 via one or more openings 513 a, 513 b, 514 a, 514 b. The openingscan be provided adjacent to the housing 501 (e.g., openings 513 a, 513b) such that the inner wall 511 a of the pressure relief structure isnot in contact with the bottom wall of the housing 501. In someexamples, the bottom wall can be the positive current collector 508. Theopenings can also be provided at some predetermined distance from thebottom wall of the housing 501 (e.g., openings 514 a, 514 b). Forexample, the inner wall 511 a can be attached to the bottom wall of thehousing and only have openings 514 a, 514 b.

The holes may be circular or of any other shape allowing the cathodematerial to flow through the holes. For example, circular holes may bepreferred to minimize drag on the flowing cathode material. The cathodematerial may flow through the holes as indicated by arrows 515, andupward in the pressure relief structure as indicated by arrows 516.

Combinations and/or a plurality of openings 513 a, 513 b, 514 a, 514 bcan be provided along the inner wall of the annular pressure reliefchamber 511. The holes may be provided at different axial distances fromthe bottom wall of the housing and may be of varying size. For example,the holes may be spaced to prevent the intermetallic layer 510 from“bottoming out”, i.e., from reaching the uppermost level of the holes(which may be near the bottom of the first chamber), and blocking theriser pipe inlet (the area around arrows 515).

The pressure relief structure can have a top wall 511 c. The top wall511 c can close the pressure relief structure to prevent material insidethe riser pipe from spilling over the top of the riser pipe. In somecases, the wall 511 b may be formed separately from the housing. Forexample, the walls 511 a, 511 b, and 511 c can be integrally formed asan annular tube with a closed top and an open bottom (e.g., openings 513a, 513 b), or as an annular tube with closed top and bottom but withperforations or holes near the bottom (e.g., openings 514 a, 514 b). Insome examples, one or more parts or all of the pressure relief structuremay be formed of one or more materials different than the housing 501.One or more parts or all of the pressure relief structure may be formedof an electrically insulating material, such as the electricallyinsulating materials described elsewhere herein.

With continued reference to FIG. 5, the cathode material in the riserpipe is not in contact with to the electrolyte 504. Further, the cathodematerial is electrically isolated from the electrolyte and the anode.When the cathode material is electrically conductive (e.g., a liquidmetal cathode material), the cathode material in the riser pipe (secondchamber) can be electrically connected with the cathode material in thefirst chamber. In some cases, such as, for example, when an unsheathedhousing is employed as described elsewhere herein, only the wall 511 bmay be electrically insulating; the walls 511 b and 511 c may beelectrically conductive. The wall 511 c may only be electricallyconductive if it is to not contact the electrolyte at any point.

The cathode material may rise in the pressure relief structure 511 to aheight h. The height h may vary around the circumference of the pressurerelief structure. The height h can be related to the volume change ofthe cathode (i.e., the liquid and solid cathode materials 505 andintermetallic layer 510). For example, the cathode materials 505 and 510can have a volume V₁ when charged, and a volume V₂ when discharged. Theheight h can be related to the volume difference V₂-V₁ and thecross-sectional area of the pressure relief structure. The annularpressure relief structure in FIG. 5 can have a width w, and an arearelated to w and the circumference of the annular structure. Thedimensions of the pressure relief structure, e.g., w, may be such thatthe cathode material can easily enter and rise in the structure. Forexample, the pressure relief structure can be dimensioned to minimizecapillary wicking effects, and to ensure that the cathode materialexperiences minimal drag forces. The pressure relief structure can bedimensioned to accommodate a predetermined amount of cathode material.For example, the pressure relief structure may be dimensioned toaccommodate less than 10%, less than 25%, less than 50%, or less than75% of maximum volume or mass of the cathode material or of the liquidcathode material.

In some cases, the addition of the riser pipe decreases the gap betweena first negative electrode end 503 a and an adjacent wall (e.g., thewall 511 a in FIG. 5), which may contribute to enhanced side wall creepof the liquid cathode material. To prevent the cathode material fromclimbing the pressure relief structure 511 along the wall facing thefirst chamber and shorting to the anode from the sides (i.e., climbingupward in FIG. 5, parallel and on the opposite side of the wall 511 afrom the arrows 516), the pressure relief structure(s) may be isolatedfrom the anode by a sheath (e.g., carbon or metal nitride or othersheath materials described herein) or coating of material (e.g., PVD orCVD coating of a high temperature material), which is not readily wet bythe cathode material. In some cases, the material may provide a surfacetexture or chemistry that interacts with the intermetallic material,e.g., the intermetallic may easily slide along the surface.

Conversely, one or more parts of the pressure relief structure, e.g.,the surfaces defining the chamber of the riser pipe, may be formed ofand/or coated with a material that is readily wet by the cathode toensure smooth flow of the cathode material in the riser pipe. Thematerial can be inert. In some cases, the material may have desiredreactivity with the cathode material. In some cases, the inlet and/orthe openings 513 a, 513 b, 514 a, 514 b can be coated with a materialthat prevents the intermetallic from sliding into the riser pipe. Theinlet and/or the openings 513 a, 513 b, 514 a, 514 b may be covered witha mesh. The inlet and/or the openings 513 a, 513 b, 514 a, 514 b maycomprise one or more valves or valve-like features. For example, theinlet and/or the openings can be configured to allow flow into the riserpipe above a certain hydraulic pressure value (e.g., duringdischarging), and to allow flow from the riser pipe into the firstchamber (e.g., during charging) at a relatively lower pressure.

Alternative configurations of the pressure relief mechanism may includeexternal pressure relief structures, such as, for example, a riser pipemounted externally to the housing 501 and in fluid communication withthe first chamber via one or more the openings 513 a, 513 b, 514 a, 514b, ducts or connectors. Further examples of pressure relief structuresinclude a shelf with an enlarged area for the intermetallic to grow(FIG. 6A), mechanical crumple zones which can contract and expand as anaccordion (FIG. 6B), and a cell design including flexibility or “give”of the cell body or housing.

With reference to FIG. 6A, an electrochemical cell or battery 600comprises a housing 601, a conductive feed-through (i.e., conductor,such as a conductor rod) 602 that passes through an aperture in thehousing 601 and is in electrical communication with a liquid metalnegative electrode 603. The cell 600 further comprises a liquid metalpositive electrode 605, and a liquid metal electrolyte 604 between theelectrodes 603, 605. The cell comprises a negative current collector 607and a positive current collector 608 that are in electricalcommunication with the negative electrode 603 and positive electrode605, respectively. During discharge of the cell 600, a solid (orsemi-solid) intermetallic layer 610 forms adjacent to the positiveelectrode 605. The intermetallic layer can develop by growinghorizontally along an interface of the electrolyte 604 and the positiveelectrode 605. The expansion may be axially symmetrical or asymmetricalwith respect to an axis of symmetry 609. The electrolyte 604 andintermetallic layer 610 meet at a first interface 610 a, and theintermetallic layer 610 and the positive electrode 605 meet at a secondinterface 610 b. During discharge of the cell 600, the intermetalliclayer 610 can bow, distort or move along a direction indicated by arrows612. The housing 601 can include a shelf or cavity to house theintermetallic layer 610 upon growth of the intermetallic layer 610during discharge of the cell 600. The cavity can be aligned with abottom portion of the housing 601 (as shown). The cavity can include awall portion that expands into a void space (white dashed lines) whenthere is a build-up of pressure in the positive electrode 605. The wallportion can be spring loaded, for example, to (1) provide a resistiveforce to prevent the wall portion from expanding if the pressure in thepositive electrode 605 is below a given pressure, (2) enable the wallportion to expand the pressure in the positive electrode 605 is at orabove the given pressure, and (3) provide a restorative force to returnthe wall portion to its original position when the pressure in thepositive electrode 605 has decreased to below the given pressure. As analternative, the cavity can be aligned with an interface between theelectrolyte 604 and the cathode 605.

With reference to FIG. 6B, in an alternative configuration, the housing601 includes mechanical crumple zones (dashed lines) that can expand andcontract upon growth and shrinkage of the intermetallic layer 610 duringdischarge and charge, respectively, of the cell 600. The crumple zonescan include voids that enable the electrodes 603, 605 and electrolyte604 to flow into upon expansion of the electrodes 603, 605 andelectrolyte 604.

Pressure relief can be readily applied to cells or batteries of varioussize scales. In an example, the annular riser pipe in FIG. 5 isimplemented in a nominal 4 inch, nominal 20 Ah cell (D1=2.75 inches, w=6mm wide, D1+w=3.03 inches, D2=3.5 inches) with Li∥Sb,Pb chemistry with anegative liquid metal electrode (anode during discharge) comprising 9.5grams of Li, a positive liquid metal electrode (cathode duringdischarge) comprising 361.5 grams of 40:60 mol % Sb:Pb, a liquid metalelectrolyte comprising 219.5 grams of 22:31:47 mol % LiF:LiCl:LiBr, anda solid intermetallic layer comprising Li₃Sb formed at an interface ofthe liquid metal electrolyte and the positive liquid metal electrodeduring discharge. The liquid Pb alloy is allowed to “rise up” into theannular riser pipe as a result of expansion of the positive liquid metalelectrode due to a pressure buildup. The concentric wall design iseffective at relieving cathode pressure, and the amount of materialbetween the walls is consistent with the volume expansion expected fromLi alloying with Sb:Pb. Analogously, during charging, the material inthe riser pipe can reversibly contract from the riser pipe. Otherexamples of cell sizes include, for example, a nominal 16 inch cell.

Mechanical Modification of Intermetallic Shape and Morphology

In another aspect of the disclosure, mechanical modifications ofelectrochemical cells (or batteries) are provided. The mechanicalmodifications can be applied, for example, in liquid metal batteriesdescribed herein. Examples include application of the mechanicalmodifications to positive battery electrodes in liquid metal batteries,e.g., for controlling interfaces during battery discharging, when thepositive battery electrode functions as a cathode. The mechanicalmodifications may be utilized to improve battery performance (e.g.,charge cycling), battery longevity and/or to prevent certain batteryfailure modes. In other examples, mechanical modifications can beapplied in alternative systems, such as, for example, in any energystorage device or energy transformation device with multiple phases(e.g., between a liquid and a solid) and phase interfaces which, whereinthe phases and phase interfaces may be formed and/or transformed duringoperation. Operation may include charging, discharging, heating, coolingor any other change in state of the device.

In an example, mechanical modifications are provided for a positiveelectrode, such as the positive liquid metal electrode 405 in FIG. 4.During discharging, the positive liquid metal electrode can function asa cathode, and the negative liquid metal electrode 403 can function asan anode. As described elsewhere herein, the solid layer 410 may formatop the liquid cathode during discharge, and pressure forces from theliquid metal cathode and/or internal stresses in the layer itself maycause undesirable morphologies of the solid layer 410, e.g., bowing orbulging of the solid layer, and/or sudden, uncontrolled pressure-inducedcracks that can inhibit cell operability.

FIG. 7A a cross-sectional side view of an electrochemical cell 700 witha bowing or bulging solid intermetallic layer 710 formed adjacent to apositive liquid metal electrode 705 during discharging, as describedelsewhere herein. In an example, the battery cell 700 can have anaxially symmetric, circular cross-section when viewed from above (“topview” in FIG. 7A). The battery cell can comprise a negative liquid metalelectrode 703, a negative current collector 707, a liquid metalelectrolyte 704, the positive liquid metal electrode 705 and a positivecurrent collector 708. Uncontrolled and unintended formation of theintermetallic layer 710 may cause failure of electrochemical cells orbatteries (e.g., liquid metal battery cells with chemistries such asLi∥Sb,Pb), because the intermetallic solid can grow into structures thatform a short between a negative liquid metal electrode 703 and/or anegative current collector 707 and the positive liquid metal electrode705. During discharge, the negative liquid metal electrode 703 can be ananode and the positive liquid metal electrode 705 can be a cathode.

The cathode morphology may depend on the size of the cell or battery700. In smaller cells (e.g., a nominal 4 inch liquid metal battery cellwith Li∥Sb,Pb chemistry), the cathode morphology may include an bulged(bowed) intermetallic layer with a maximum height at or near the centerof the cell, as shown in FIG. 7A. The liquid metal cathode 705 can fillcell cavity below the arc (i.e., between the intermetallic layer 710,and the bottom wall of the housing 701 and/or the positive currentcollector 708). In larger cells, the intermetallic layer may developirregular undulations with several height maxima distributed over anactive surface or interface (e.g., the interface between the electrolyte704 and the liquid metal cathode 705) of the cell. In some cases, theseundulating morphologies may be problematic during cell operation,because the crests of the undulating cathode (i.e., the undulatingintermetallic layer of the cathode) can contact the anode 703 and/or thenegative current collector 707, which can irreversibly short a cell. Insome examples, the troughs of the undulating features appear to bepinned at the sidewalls of the cell (i.e., at the sidewalls of thehousing 701). In one example, the cathode morphology in a nominal 1 inchliquid metal battery cell with Li∥Sb,Pb chemistry can be relatively flatand controlled, while deviation from flatness can increase withincreasing cell size.

FIG. 7B is a cross-sectional side view of the electrochemical cell orbattery 700 outfitted with a mechanical modification, such as a post717. The added mechanical modification (e.g., an appropriate physicalprotrusion) may interact with the cathode-intermetallic interface(including the intermetallic), thereby modifying thecathode-intermetallic morphology into a form more amenable to extendedcell operation (e.g., encouraging a more flat, uniform intermetalliclayer) by introducing additional pin or “attachment points” in additionto the sidewalls of the housing. Thus, the intermetallic can be allowedto form, but the shape or geometry can be disrupted such that the formedintermetallic layer is flatter (e.g., by forming smaller bulges orundulations). For example, the intermetallic can be forced to formsmaller and lower bulging features (FIG. 7B) between attachment pointsinstead of the single feature across an entire width, diameter or othercharacteristic dimension D of the cell (FIG. 7A). The presence of one ormore disruptors or an array of disruptors may furthermore affect thethickness of the intermetallic layer and/or location of the heightmaxima. For example, a height maximum may not occur symmetricallybetween attachment points, and may depend on the type of attachmentpoint (e.g., the location of a height maximum between a wall attachmentpoint and a post attachment point may be skewed toward one of the twoattachment points). In some cases, a complicated morphology of theintermetallic layer may result from the use of a set or an array ofattachment points. In another example, the intermetallic layer may bethinner near an attachment point, or the thickness may depend on thetype of attachment point.

One or more mechanical modifications (also “disruptors” or“intermetallic disruptors” herein) may be provided in the cell orbattery 700, including, but not limited to, one or more vertical posts,an array of vertical posts (e.g., two, three or more posts 717, a bed ofnails), one or more plates, a grid of interleaved plates configured toform compartments on the cathode (e.g., egg carton-like or grid-likestructure), one or more structural pieces, an array of structural pieces(e.g., an array of angled iron pieces lying on their side on the cellbottom), stamped structures (e.g., stamped ridges) and/or othermechanical disruptor type or configuration capable of mechanicallyinterfering with the growth of the intermetallic layer to enablemanaging the cathode morphology during cycling. In some cases, one ormore features may be provided elsewhere within the cell 700 that arecomplementary to a particular cathode disruptor configuration or to acell morphology that results from a particular cathode disruptorconfiguration. For example, if a stamped ridge configuration or an arrayof posts is used on the cathode, giving rise to a particular wave-likepattern, the negative current collector 707 may be formed with a similarwave-like pattern such that the distance between any point on an uppersurface of the intermetallic layer 710 and a vertically opposite (i.e.,at the same position x) point on the negative current collector 707remains approximately constant across the cell.

FIG. 7C is a cross-sectional side view of the electrochemical cell orbattery 700 outfitted with ridges 718, another example of a mechanicalmodification of the cathode. Although a flat layer is shown, theintermetallic layer may have a morphology determined by the ridgestructure. The disruptors may be formed of any suitable materialincluding, but not limited to, materials suitable forhousings/containers, current collectors, sheaths, or any other featuresof the disclosure. Individual disruptors and/or disruptor types may ormay not be formed of the same material(s). The disruptors may beprovided together with one or more components of cell 700. For example,the disruptors may be provided on bottom wall of the housing 701 and/oron the positive current collector 708. One or more disruptor featuresmay be integrated with one or more cell components, while one or moreother disruptor features may be integrated with another one or more cellcomponents. The disruptor features or parts thereof may be formedseparately and subsequently attached to one or more cell components.Alternatively, the disruptor features or parts thereof may be integrallyformed with one or more cell components. For example, ridges may bestamped into the positive current collector 708, and an additionaldisruptor grid may be attached to or contacted with the modifiedpositive current collector, thus forming a composite disruptorconfiguration. In another example, a first portion of a single type ofdisruptor may be integrally formed with the housing 701, while a secondportion may be attached to the first portion during cell assembly. Anycombination of disruptor material, formation or assembly can be used.Furthermore, mechanical modification can be advantageously incorporatedinto an existing cell manufacturing process. For example, ridges orposts can be introduced during stamping or hydroforming of a cellbottom. In another example, the attachment and welding of posts can beautomated or achieved using a robot.

Individual disruptor features (e.g., individual posts) may be spacedapart in a predetermined pattern. For example, a spacing betweenindividual disruptor features in array can be determined to achieve apredetermined maximum height and/or a predetermined pattern of theintermetallic layer. Once an appropriate spacing is determined, thearray spacing may be scaled between different cell geometries. Forexample, the same spacing can be used, or the spacing can be scaled bycell diameter or width, cell area, etc. In some cases, array spacing canbe scaled according to current density and/or other cell operatingparameters. The disruptor features may be spaced apart uniformly, orstochastically. The disruptor features may be spaced apart to achieve adesired surface density of disruptor features (e.g., an average surfacedensity of 1.5 posts per square centimeter of the bottom surface of thehousing 701).

In an example, the disruptor of FIG. 7B is implemented in a nominal 4inch, nominal 20 Ah cell (D1=2.75 inches, w=6 mm wide, D1+w=3.03 inches,D2=3.5 inches) with Li∥Sb,Pb chemistry with a negative liquid metalelectrode (anode during discharge) comprising 15.8 grams of Li, apositive liquid metal electrode (cathode during discharge) comprising480.3 grams of 40:60 mol % Sb:Pb, a liquid metal electrolyte comprising300.2 grams of 22:31:47 mol % LiF:LiCl:LiBr, and a solid intermetalliclayer comprising Li₃Sb formed at an interface of the liquid metalelectrolyte and the positive liquid metal electrode during discharge. Ina discharged state, the Li∥Sb,Pb cell can have a intermetallic phase anda metallic Sb,Pb alloy. In experiments with a centered steel post designand an off-center steel post design, the peak of the intermetallic layeris translated from the center of the cell as a result of the presence ofthe post. In the case of the off-center post design, the maximum heightof the bulging intermetallic layer can be shifted in the direction ofthe post, and the intermetallic layer can be thinnest near the post. Anarray of vertical posts extending from the cell bottom and a grid ofinterleaved metal plates, producing several compartments in the cellbottom similar to an egg carton have also been tested. Other examples ofcell sizes include, for example, a nominal 16 inch cell.

Aspects of the disclosure may be synergistically combined. For example,a pressure relief mechanism can be used in concert with otherintermetallic management strategies, such as the use of mechanicaldisruptors described herein. The pressure relief mechanism may enhancethe performance of the disruptors by reducing the tendency of cathodematerial to be forced through induced defects in the intermetalliclayer. For example, in Li∥Sb,Pb systems, the use of disruptors alone maycause defects in the solid intermetallic layer that do not result in acontrolled pressure release, causing liquid cathode material to breakthrough the defects with substantial force. The resulting upward motionof liquid cathode material can be a limiting factor to cell operabilityand lifespan. The use of pressure relief mechanisms of the disclosuremay alleviate the pressure buildup and enable improved (or modified)disruptor performance. For example, smaller and/or otherwise distributeddisrupters may be used during operation with lesser pressure buildup.

Any aspects of the disclosure described in relation to cathodes mayequally apply to anodes at least in some configurations. Similarly, oneor more battery electrodes and/or the electrolyte may not be liquid inalternative configurations. In an example, the electrolyte can be apolymer or a gel. In a further example, at least one battery electrodecan be a solid or a gel. Furthermore, in some examples, the electrodesand/or electrolyte may not include metal. Aspects of the disclosure areapplicable to a variety of energy storage/transformation devices withoutbeing limited to liquid metal batteries.

Electrochemical cells of the disclosure may be capable of storing(and/or taking in) a suitably large amount of energy. In some instances,a cell is capable of storing (and/or taking in) about 1 Wh, about 5 Wh,25 Wh, about 50 Wh, about 100 Wh, about 500 Wh, about 1 kWh, about 1.5kWh, about 2 kWh, about 3 kWh, or about 5 kWh. In some instances, thebattery is capable of storing (and/or taking in) at least about 1 Wh, atleast about 5 Wh, at least about 25 Wh, at least about 50 Wh, at leastabout 100 Wh, at least about 500 Wh, at least about 1 kWh, at leastabout 1.5 kWh, at least about 2 kWh, at least about 3 kWh, or at leastabout 5 kWh. It is recognized that the amount of energy stored in anelectrochemical cell and/or battery may be less than the amount ofenergy taken into the electrochemical cell and/or battery (e.g., due toinefficiencies and losses).

The compilation of cells (i.e., battery) can include any suitable numberof cells, such as at least about 2, at least about 5, at least about 10,at least about 50, at least about 100, at least about 500, at leastabout 1000, at least about 5000, at least about 10000, and the like. Insome examples, a battery includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20,30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900,1000, 2000, 5000, 10,000, 20,000, 50,000, 100,000, 500,000, or 1,000,000cells.

Batteries of the disclosure may be capable of storing a suitably largeamount of energy for use with a power grid (i.e., a grid-scale battery)or other loads or uses. In some instances, a battery is capable ofstoring (and/or taking in) about 5 kWh, 25 kWh, about 50 kWh, about 100kWh, about 500 kWh, about 1 MWh, about 1.5 MWh, about 2 MWh, about 3MWh, or about 5 MWh. In some instances, the battery is capable ofstoring (and/or taking in) at least about 5 kWh, at least about 25 kWh,at least about 50 kWh, at least about 100 kWh, at least about 500 kWh,at least about 1 MWh, at least about 1.5 MWh, at least about 2 MWh, atleast about 3 MWh, or at least about 5 MWh.

In some instances, the cells and cell housings are stackable. Anysuitable number of cells can be stacked. Cells can be stackedside-by-side, on top of each other, or both. In some instances, at leastabout 10, 50, 100, or 500 cells are stacked. In some cases, a stack of100 cells is capable of storing at least 50 kWh of energy. A first stackof cells (e.g., 10 cells) can be electrically connected to a secondstack of cells (e.g., another 10 cells) to increase the number of cellsin electrical communication (e.g., 20 in this instance). In someinstances, the energy storage device comprises a stack of 1 to 10, 11 to50, 51 to 100, or more electrochemical cells.

The electrochemical cells can be arranged in series and/or parallel toform an electrochemical energy storage system (i.e., battery). Theenergy storage system can comprise modules, packs, cores, and/or pods ofelectrochemical cells surrounded by a frame.

Another aspect of the present disclosure provides a system that isprogrammed or otherwise configured to implement the methods of thedisclosure. FIG. 8 shows a system 800 programmed or otherwise configuredto one or more process parameters of an energy storage system. Thesystem 800 includes a computer server (“server”) 801 that is programmedto implement methods disclosed herein. The server 801 includes a centralprocessing unit (CPU, also “processor” and “computer processor” herein)805, which can be a single core or multi core processor, or a pluralityof processors for parallel processing. The server 801 also includesmemory 810 (e.g., random-access memory, read-only memory, flash memory),electronic storage unit 815 (e.g., hard disk), communication interface820 (e.g., network adapter) for communicating with one or more othersystems, and peripheral devices 825, such as cache, other memory, datastorage and/or electronic display adapters. The memory 810, storage unit815, interface 820 and peripheral devices 825 are in communication withthe CPU 805 through a communication bus (solid lines), such as amotherboard. The storage unit 815 can be a data storage unit (or datarepository) for storing data. The server 801 can be operatively coupledto a computer network (“network”) 830 with the aid of the communicationinterface 820. The network 830 can be the Internet, an internet and/orextranet, or an intranet and/or extranet that is in communication withthe Internet. The network 830 in some cases is a telecommunicationand/or data network. The network 830 can include one or more computerservers, which can enable distributed computing, such as cloudcomputing. The network 830, in some cases with the aid of the server801, can implement a peer-to-peer network, which may enable devicescoupled to the server 801 to behave as a client or a server. The server801 can be coupled to an energy storage system 835 either directly orthrough the network 830.

The storage unit 815 can store process parameters of the energy storagesystem 835. The server 801 in some cases can include one or moreadditional data storage units that are external to the server 801, suchas located on a remote server that is in communication with the server801 through an intranet or the Internet.

The server 801 can communicate with one or more remote computer systemsthrough the network 830. In the illustrated example, the server 801 isin communication with a remote computer system 840. The remote computersystem 840 can be, for example, a personal computers (e.g., portablePC), slate or tablet PC (e.g., Apple® iPad, Samsung® Galaxy Tab),telephone, Smart phone (e.g., Apple® iPhone, Android-enabled device,Blackberry®), or personal digital assistant.

In some situations, the system 800 includes a single server 801. Inother situations, the system 800 includes multiple servers incommunication with one another through an intranet and/or the Internet.

Methods as described herein can be implemented by way of machine (orcomputer processor) executable code (or software) stored on anelectronic storage location of the server 801, such as, for example, onthe memory 810 or electronic storage unit 815. During use, the code canbe executed by the processor 805. In some cases, the code can beretrieved from the storage unit 815 and stored on the memory 810 forready access by the processor 805. In some situations, the electronicstorage unit 815 can be precluded, and machine-executable instructionsare stored on memory 810. Alternatively, the code can be executed on thesecond computer system 840.

The code can be pre-compiled and configured for use with a machine havea processer adapted to execute the code, or can be compiled duringruntime. The code can be supplied in a programming language that can beselected to enable the code to execute in a pre-compiled or as-compiledfashion.

Aspects of the systems and methods provided herein, such as the server801, can be embodied in programming. Various aspects of the technologymay be thought of as “products” or “articles of manufacture” typicallyin the form of machine (or processor) executable code and/or associateddata that is carried on or embodied in a type of machine readablemedium. Machine-executable code can be stored on an electronic storageunit, such memory (e.g., read-only memory, random-access memory, flashmemory) or a hard disk. “Storage” type media can include any or all ofthe tangible memory of the computers, processors or the like, orassociated modules thereof, such as various semiconductor memories, tapedrives, disk drives and the like, which may provide non-transitorystorage at any time for the software programming. All or portions of thesoftware may at times be communicated through the Internet or variousother telecommunication networks. Such communications, for example, mayenable loading of the software from one computer or processor intoanother, for example, from a management server or host computer into thecomputer platform of an application server. Thus, another type of mediathat may bear the software elements includes optical, electrical andelectromagnetic waves, such as used across physical interfaces betweenlocal devices, through wired and optical landline networks and overvarious air-links. The physical elements that carry such waves, such aswired or wireless links, optical links or the like, also may beconsidered as media bearing the software. As used herein, unlessrestricted to non-transitory, tangible “storage” media, terms such ascomputer or machine “readable medium” refer to any medium thatparticipates in providing instructions to a processor for execution.

Hence, a machine readable medium, such as computer-executable code, maytake many forms, including but not limited to, a tangible storagemedium, a carrier wave medium or physical transmission medium.Non-volatile storage media include, for example, optical or magneticdisks, such as any of the storage devices in any computer(s) or thelike, such as may be used to implement the databases, etc. shown in thedrawings. Volatile storage media include dynamic memory, such as mainmemory of such a computer platform. Tangible transmission media includecoaxial cables; copper wire and fiber optics, including the wires thatcomprise a bus within a computer system. Carrier-wave transmission mediamay take the form of electric or electromagnetic signals, or acoustic orlight waves such as those generated during radio frequency (RF) andinfrared (IR) data communications. Common forms of computer-readablemedia therefore include for example: a floppy disk, a flexible disk,hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD orDVD-ROM, any other optical medium, punch cards paper tape, any otherphysical storage medium with patterns of holes, a RAM, a ROM, a PROM andEPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wavetransporting data or instructions, cables or links transporting such acarrier wave, or any other medium from which a computer may readprogramming code and/or data. Many of these forms of computer readablemedia may be involved in carrying one or more sequences of one or moreinstructions to a processor for execution.

Various parameters of an energy storage system can be presented to auser on a user interface (UI) of an electronic device of the user.Examples of UI's include, without limitation, a graphical user interface(GUI) and web-based user interface. The UI (e.g., GUI) can be providedon a display of an electronic device of the user. The display can be acapacitive or resistive touch display. Such displays can be used withother systems and methods of the disclosure.

Methods of the disclosure can be facilitated with the aid ofapplications (apps) that can be installed on electronic devices of auser. An app can include a GUI on a display of the electronic device ofthe user. The app can be programmed or otherwise configured to performvarious functions of the system.

Methods for Transporting Energy Storage Systems

Another aspect of the present disclosure provides methods fortransporting energy storage systems. In some cases, the energy storagedevices are transported with molten metal electrodes (e.g., at a hightemperature of at least 250° C., at least 400° C., at least 500° C., orat least 600° C.). The energy storage devices can also be transported atambient temperature (e.g., with the electrodes being solid and notmolten) and heated at the site of operation to melt the metalelectrodes.

The energy storage devices can be transported in any suitable mannerincluding fully assembled or in pieces to be assembled at the site ofoperation. The energy storage devices can be transported on any suitablevehicle, such as a truck (including on a trailer pulled by a truck), ona train, on a ship, on an airplane, on a helicopter, by a robot, and thelike. FIG. 9 shows an energy storage device 905 that is assembled 900and placed on a vehicle 910. In this case the vehicle includes a truck915 and a trailer 920 pulled by the truck. The vehicle can transport theenergy storage device 925 from an initial location 930 to a site ofinstallation and/or operation 935 along any suitable path (e.g., alongroads, railroad tracks, shipping routes and the like).

The energy storage devices can be transported any distance such as atleast about 1 mile, at least about 10 miles, at least about 100 miles,at least about 1,000 miles or at least about 10,000 miles. The energystorage devices can be transported at any speed including at least about5 miles per hour (mph), at least about 10 mph, at least about 20 mph, atleast about 40 mph, at least about 60 mph, at least about 150 mph, or atleast about 500 mph.

An energy storage device of the present disclosure, including anelectrochemical cell (“cell”) of the energy storage device, can beconfigured for transport. In some cases, the cell does not have avoltage and cannot pass current while being transported (e.g., on atruck at room temperature). The cell may not have an appreciable ordetectable voltage during transport, and the cell may not pass anappreciable or detectable current during transport. This can beadvantageous since the cells are electrically inert and cannot short.

An electrochemical cell can comprise chemical components that generate apotential difference when a system comprising the cell is heated (e.g.,to approximately 250° C. or 450° C. or 500° C.). While at roomtemperature, the electrolyte in the cell can be solid and/or incapableof conducting ions necessary to facilitate either the charge ofdischarge reactions. The system does not pass current (e.g., even if theelectrode terminals are shorted), and does not have an inherent cellvoltage. When the temperature is elevated, the non-aqueous (non waterbased) electrolyte melts and/or becomes an ionic conductor, thusenabling the cell to accept or provide current and charge or discharge.When at operating temperature and when the electrolyte is molten orionically conductive and if the cell is above 0% state of charge, thebattery can have a non-zero cell voltage of around 0.9 volts in somecases.

An advantage of a cell that does not exhibit a cell voltage and isunable to accept or supply current while at room temperature is that thesafety risks associated with shipping batteries are reduced. Even in theevent that the cells are jostled and are externally shorted, the cellsdo not discharge and cannot be charged.

In some cases, the system comprises a metallic crucible that acts as oneelectrode and a dielectrically separated region that forms the secondelectrode. At room temperature, the electrodes are physically separatedby solid chemicals that are inert and do not inherently generate apotential between the two electrodes. As temperature is raised portionsof the solid electrolyte can undergo a change in electricalcharacteristics (such as a phase transition) that results in a potentialdifference forming between the electrodes. When temperature ismaintained at approximately this range, the system can be capable ofsourcing (discharging) or sinking (recharging) current. When thetemperature is brought back to room temperature, the chemical media canundergo another phase transition that brings potential difference tozero between the electrodes and also increases ionic resistancepreventing flow of current.

Energy storage devices (or batteries) of the present disclosure can bereliably safe during transportation and handling from a pickup locationto a delivery location. Physical short circuits or other externallyinduced abuse conditions (e.g., puncture, shock, vibration, etc.) havelittle to no effect on safety or operation of the system when theseconditions are induced at room temperature.

An electrochemical energy storage device of the present disclosure(including a cell of the device) may not be capable of being charged,being discharged, or having an electrical potential during transport.This may be accomplished by transporting (or shipping) the energystorage device at a temperature that is reduced with respect to anoperating temperature of the energy storage device.

For example, an electrochemical energy storage device can comprise ananode and a cathode, and an electrolyte between the anode and thecathode. The device may not be capable of conducting ions at a firsttemperature and capable of conducting ions at a second temperature. Thefirst temperature may be maintained during transport of theelectrochemical energy storage device.

The anode can comprise lithium, potassium, magnesium and/or calcium. Thecathode can comprise antinomy, tin, tellurium, bismuth and/or lead.

In some embodiments, at least part of the device is a solid at the firsttemperature and a liquid at the second temperature. The at least part ofthe device can be an electrolyte.

In some cases, the first temperature is room temperature. In some cases,the first temperature is less than about 100° C. In some cases, thesecond temperature is at least about 250° C. In some cases, the secondtemperature is at least about 500° C.

The device of the present disclosure may not be capable of beingcharged, being discharged, or having an electrical potential at thefirst temperature. In some instances, the device has a positive terminaland a negative terminal, and shorting the terminals does not dischargethe device at the first temperature. In some cases, the device does notdischarge when the device is punctured, vibrated, shorted, or shocked.

In another aspect of the present disclosure, an electrochemical energystorage device comprises a negative electrode and a positive electrode,and an electrolyte between the negative and positive electrodes. Thedevice has a first potential difference between the electrodes at afirst temperature of less than about 50° C. and a second potentialdifference between the electrodes at a second temperature of at leastabout 250° C. The second potential difference is greater than the firstpotential difference.

In some cases, the first potential difference is less than or equal toabout 2.5 volts, 2 volts, 1.5 volts, 1.2 volts, 1 volt, 0.9 volts, 0.8volts, 0.7 volts, 0.6 volts, 0.5 volts, 0.4 volts, 0.3 volts, 0.2 volts,0.1 volts, or less. The first potential difference can be about 0 volts.

The second voltage can be greater than 0 volts, or greater than or equalto about 0.1 volts, 0.2 volts, 0.3 volts, 0.4 volts, 0.5 volts, 0.6volts, 0.7 volts, 0.8 volts, 0.9 volts, 1 volt, 1.2 volts, 1.5 volts, 2volts, or 2.5 volts.

The negative electrode can comprise lithium, potassium, magnesium and/orcalcium. The positive electrode can comprise antinomy, tin, tellurium,bismuth and/or lead.

The electrochemical energy storage device of the present disclosure canbe comprised in an array of energy storage devices as part of an energystorage system. In some cases, the electrochemical energy storage deviceis an energy storage cell, and the energy storage system comprises aplurality of energy storage cells.

The present disclosure provides methods for transporting energy storagedevices, and installing the energy storage devices for use in an energystorage system. The energy storage system can be electrically coupled toa power source and a load, such as, for example, a power grid. Theenergy storage system can store energy from the power source for usewith the load.

FIG. 10 illustrates a method 1000 for forming an energy storage systemof the present disclosure. The method 1000 comprises, in a firstoperation 1001, forming, at a first location, an energy storage devicecomprising a negative electrode and a positive electrode, and anelectrolyte between the negative electrode and the positive electrode,and placing the energy storage device on a vehicle (e.g., truck, train)that is configured to transport the energy storage device from the firstlocation to a second location. The energy storage device can be asdescribed elsewhere herein. For instance, the negative electrode,positive electrode and electrolyte can each be formed of a material thatis in the liquid at an operating temperature of the energy storagedevice.

Next, in a second operation 1002, the method 1000 comprises using thevehicle to transport the energy storage device from the first locationto the second location. Next, in a third operation 1003, at the secondlocation the energy storage device can be removed from the vehicle. Theenergy storage device can be subsequently positioned at an installationlocation, and in some cases installed into the energy storage system atthe installation location.

In some examples, the energy storage device can be electrically coupledto a power source. The power source can be selected from the groupconsisting of a power plant (e.g., nuclear power plant, coal-fired powerplant, fuel-fired power plant), a wind turbine, a photovoltaic system, ageothermal system, and a wave energy system. The power source can beconfigured to generate power from a renewable energy source ornon-renewable energy source.

The energy storage device of the present disclosure can be electricallycoupled to a load, such as a power grid. The energy storage device canthen be employed to deliver power to the load and/or store energy fromthe power source.

During transport, a potential difference between the positive electrodeand the negative electrode can be less than about 1 volt, 0.9 volts, 0.8volts, 0.7 volts, 0.6 volts, 0.5 volts, 0.4 volts, 0.3 volts, 0.2 volts,0.1 volts, or less. In some examples, the potential difference can beabout 0 volts. The potential difference can be less than 1 volt, 0.9volts, 0.8 volts, 0.7 volts, 0.6 volts, 0.5 volts, 0.4 volts, 0.3 volts,0.2 volts, 0.1 volts, or less (e.g., 0 volts) at a temperature(“transport temperature”) that is less than the operating temperature ofthe energy storage device. The energy storage device can be transportedwith the energy storage device at the transport temperature.

Liquid Metal Electrochemical Energy Storage Devices

Electrochemical cells having molten electrodes having an alkali metalcan provide receipt and delivery of power by transporting atoms of thealkali metal between electrode environments of disparate chemicalpotentials through an electrochemical pathway comprising a salt of thealkali metal. The chemical potential of the alkali metal is decreasedwhen combined with one or more non-alkali metals, thus producing avoltage between an electrode comprising the molten alkali metal and theelectrode comprising the combined alkali/non-alkali metals. Additionaldetails of the batteries can be found in U.S. Patent Publication No.2012/0104990, which is hereby incorporated by reference in its entirety.

In some cases, an electrochemical cell has three distinct phases. Thefirst phase defines a positive electrode having at least one elementother than an alkali metal. The second phase includes cations of thealkali metal, and defines two separate interfaces. The first phase is incontact with the second phase at one of the interfaces. The third phasedefines a negative electrode and includes the alkali metal. It isseparate from the first phase and in contact with the second phase atthe other interface. The first and third phases have respective volumeswhich decrease or increase at the expense of one another duringoperation of the cell. As a result the second phase is displaced from afirst position to a second position. The first, second, and third phasesmay be solid, liquid, or in a combination of solid or liquid states. Inpreferred embodiments, the alkali metal is present at respectivedisparate chemical potentials in the first and third phases, originatinga voltage between the first and third phases.

An embodiment includes an electrochemical cell having two distinctphases. The first phase defines a positive electrode and includes analkali metal, and two other elements other than the alkali metal. Thesecond liquid phase includes cations of the alkali metal, and definestwo separate interfaces. The first phase is in contact with the secondphase at one of the interfaces. In some embodiments, the first andsecond phases are solid. In other embodiments, the first and secondphases are liquid. In other embodiments, the phases are in a combinationof solid or liquid states. The alkali metal preferably is selected toexhibit a change in chemical potential when combined with the first andsecond elements. During operation of the cell to deliver or drawelectrical energy to drive transfer of the alkali metal to or from thesecond liquid phase to or from the first liquid phase, the first phasehas a volume which increases or decreases thus transferring energy to orfrom the electrochemical cell to or from an external circuit. As aresult the second phase is displaced from a first position to a secondposition.

In some cases, the two elements other than the alkali metal areindependently selected from group IVA, VA and VIA elements of thechemical periodic table. In some embodiments, these elements areselected independently from one of tin, lead, bismuth, antimony,tellurium and selenium. In other embodiments, these elements are leadand antimony. The alkali metal may be sodium or lithium or potassium.The second phase may include refractory particles distributed throughoutthe second liquid phase. Moreover, the refractory particles may includea metal oxide or metal nitride, or combinations thereof.

The second phase can include a salt of the alkali metal. The salt of thealkali metal may be selected from one or more of halide, bistriflimide,fluorosulfano-amine, perchlorate, hexaflourophosphate,tetrafluoroborate, carbonate or hydroxide.

In some instances, a method stores electrical energy transferred from anexternal circuit. To that end, the method provides at least oneelectrochemical cell having three liquid phases. The first liquid phasedefines a positive electrode and includes at least one element otherthan an alkali metal. The second liquid phase includes cations of thealkali metal, and defines two separate interfaces. The first phase is incontact with the second phase at one of the interfaces. The third liquidphase defines a negative electrode and includes the alkali metal. It isseparate from the first phase and in contact with the second phase atthe other interface. The electrochemical cell is configured to connectwith the external circuit. The external circuit is electricallyconnected to a negative pole and a positive pole of electrochemicalcell. The external circuit is operated which drives electrical energythat drives transfer of the alkali metal to or from the first liquidphase, through the second liquid phase, and to or from the third liquidphase. The first phase has a volume which decreases or increases whilethe third phase has a volume which decreases or increases respectivelythus transferring energy to and from the external circuit to theelectrochemical cell. As a result the second phase is displaced from afirst position to a second position.

A method of the present disclosure can release electrical energy fromthe electrochemical cell to an external circuit. The method includesproviding at least one electrochemical cell having three liquid phases.The first liquid phase defines a positive electrode and includes twoelements other than an alkali metal. The second liquid phase includescations of the alkali metal, and defines two separate interfaces. Thefirst phase is in contact with the second phase at one of theinterfaces. The third liquid phase defines a negative electrode andincludes the alkali metal. It is separate from the first phase and incontact with the second phase at the other interface. Theelectrochemical cell is configured to connect sequentially with externalcircuits. The external circuits are electrically connected to a negativepole and a positive pole of electrochemical cell. The external circuitsare sequentially operated to drive electrical energy to drive transferof the alkali metal to or from the third liquid phase, through thesecond liquid phase, and to or from the first liquid phase, the firstphase has a volume which increases or decreases while the third phasehas a volume which decreases or increases respectively thus transferringenergy to or from the electrochemical cell to or from the externalcircuits. As a result the second phase is displaced from a firstposition to a second position.

An electrochemical method and apparatus of the present disclosure forhigh-amperage electrical energy storage can feature a high-temperature,all-liquid chemistry. The reaction products created during charging canremain part of the electrodes during storage for discharge on demand. Ina simultaneous ambipolar electrodeposition cell, a reaction compound canelectrolyzed to effect transfer from an external power source Theelectrode elements are electrodissolved during discharge. Additionaldetails of the liquid metal batteries can be found in U.S. PatentPublication No. 2008/0044725, which is herein incorporated by referencein its entirety.

Electrochemical cells of the present disclosure having molten electrodescomprising an alkaline earth metal can provide receipt and delivery ofpower by transporting atoms of the alkaline earth metal betweenelectrode environments of disparate the alkaline earth metal chemicalpotentials. Additional details of the alkaline earth metal batteries canbe found in U.S. Patent Publication No. 2011/0014503, which is hereinincorporated by reference in its entirety.

In another aspect of the present disclosure, an energy storage devicecomprises at least one electrochemical cell having an operatingtemperature, the at least one electrochemical cell comprising: (a) aliquid negative electrode comprising a first metal; (b) a liquidelectrolyte adjacent to the liquid negative electrode; and (c) a liquidpositive electrode adjacent to the liquid electrolyte, the liquidpositive electrode comprising a second elemental metal that is differentthan the first metal. The liquid electrolyte can comprise a chargedspecies of the first metal and an oppositely charged species of thesecond metal, and the energy storage device is capable of beingtransported on a truck.

The first metal and/or the second metal can be an elemental metal (i.e.,not an alloy or compound).

In another aspect of the present disclosure, an energy storage devicecomprises a first material and a second material, where the materialsare liquid at the operating temperature of the device, the materialsconduct electricity, the materials have different densities and thematerials react with each other to form a mutual reaction compound, andthe energy storage device is capable of being transported on a truck.

In some instances, the electrolyte has a free energy of formation morenegative than that of the mutual reaction compound. In some embodiments,the electrolyte further comprises additives that lower the meltingtemperature of the electrolyte, reduces the viscosity of theelectrolyte, enhance ionic conductivity through the electrolyte, inhibitelectronic conductivity through the electrolyte or any combinationthereof.

The first material or second material can further comprise additivesthat enable electrochemical monitoring of the extent of discharge of thedevice.

In another aspect of the present disclosure, an energy storage devicecomprises a molten salt, where a liquid electronic conductor isextracted from the molten salt by oxidation and metal is extracted fromthe molten salt by reduction and the energy storage device is capable ofbeing transported on a truck.

In some cases, the liquid electronic conductor is antimony. In someembodiments, the liquid electronic metal is magnesium.

In another aspect of the present disclosure, an electrometallurgicalcell comprises a positive electrode and a negative electrode, where theelectrodes are liquid, the reactants of reactions that occur at theelectrodes are liquid, and the products of reactions that occur at theelectrodes are liquid, and where the electrometallurgical cell iscapable of being transported on a truck.

In some cases, an electrode comprises a material and a reaction thatoccurs at the electrode produces the material, thereby enlarging theelectrode. In some embodiments, an electrode comprises a material and areaction that occurs at the electrode consumes the material, therebyconsuming the electrode. In some embodiments, the electrodes do notcomprise a solid.

The products of reactions that occur at the electrodes may not comprisea gas. In some embodiments, the cell has a current density of at least100 mA/cm² and an efficiency of at least 60%, at least 70%, at least80%, or at least 90%.

In another aspect of the present disclosure, an energy storage devicecapable of being transported on a truck and having a power capacity ofgreater than 1 MW comprises: (a) a physical footprint smaller than about100 m²/MW; (b) a cycle life greater than 3000 deep discharge cycles; (c)a lifespan of at least 10 years; (d) a DC-to-DC efficiency of at least65%; (e) a discharge capacity of at most 10 hours; and (f) a responsetime of less than 100 milliseconds.

The energy storage device of the present disclosure may comprise aliquid metal. In some cases, the device comprises a liquid metal anode,a liquid metal cathode, and a liquid metal electrolyte. The device canbe transported with some or all of the anode, cathode and electrolytebeing in the solid state.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid electrode, the electrode comprising an additive,where the electrode is consumed and the additive is concentrated byoperation of the device, and where a property of the device isdetermined by of the concentration of the additive, and where the energystorage device is capable of being transported on a truck.

In some cases, the property of the device is the extent of discharge ofthe device. In some embodiments, the additive comprises lead. In someembodiments, the open voltage of the cell drops when the additive isconcentrated.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid antimony electrode, a steel container and a layer ofiron antimonide disposed therebetween, where the device is operated atless than 738° C., and where the energy storage device is capable ofbeing transported on a truck.

In some instances, the iron antimonide is electronically conductive andprotects the steel from corrosion.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid electrode and a current collector in contact with theelectrode, where the liquid electrode is consumed in a reaction duringoperation of the device, and where the amount of liquid electrode is instoichiometric excess relative to other reactants of the reaction suchthat the current collector is in contact with the liquid electrode whenthe reaction has proceeded to completion, and where the energy storagedevice is capable of being transported on a truck.

The current collector can be a negative current collector and thereaction comprises discharging the device.

In another aspect of the present disclosure, an energy storage devicecomprises an alkaline earth metal present in each of a positiveelectrode, a negative electrode and a liquid electrolyte, where theenergy storage device is capable of being transported on a truck.

In some instances, the alkaline earth metal is at three disparatechemical potentials in the positive electrode, the negative electrodeand the liquid electrolyte. In some cases, the alkaline earth metal is ahalide in the electrolyte. In some instances, the alkaline earth metalis an alloy in the positive electrode. In some cases, the alkaline earthmetal is elemental in the negative electrode.

In another aspect of the present disclosure, an energy storage devicecomprises an alkaline earth metal present in each of an elemental form,an alloy form and a halide form, where the energy storage device iscapable of being transported on a truck.

In some cases, the elemental form (e.g., not alloyed or a salt) is foundin a negative electrode of the device. In some embodiments, the alloyform is found in a positive electrode of the device. In someembodiments, the halide form (e.g., chloride salt) is found in anelectrolyte of the device.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid anode, a liquid cathode and a liquid electrolytedisposed therebetween, where the thickness of the electrolyte issubstantially constant through a charge-discharge cycle of the device,and the energy storage device is capable of being transported on atruck. The thickness can vary by any suitable amount during theoperation of the device including varying by less than 20%, less than10%, less than 5%, or less than 2%.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid anode, a liquid cathode and a liquid electrolytedisposed therebetween, where the thickness of the electrolyte is lessthan 50% of the thickness of the cathode or the anode, and the energystorage device is capable of being transported on a truck.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid anode, a liquid cathode, a liquid electrolyte, and acirculation producer configured to generate circulation within at leastone of the liquids, where the energy storage device is capable of beingtransported on a truck.

In some embodiments, the temperature inside the device is greater thanthe temperature outside the device and the circulation producer is athermally conductive material extending from the inside of the device tothe outside of the device.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid electrode comprising an elemental alkaline earthmetal and an electrolyte comprising a halide of the alkaline earthmetal, where the electrolyte further comprises complexing ligands, andthe energy storage device is capable of being transported on a truck.

The complexing ligands can reduce the solubility of the elementalalkaline earth metal in the halide of the alkaline earth metal.

In another aspect of the present disclosure, an energy storage devicecomprises a conductive housing comprising a conductive liquid anode, aconductive liquid cathode and an electrolyte disposed therebetween,where the interior surface of the container is not electricallyinsulated, and the energy storage device is capable of being transportedon a truck.

In some cases, the device further comprises an electrically conductivestructure that holds the conductive liquid anode or the conductiveliquid cathode away from the interior surface of the container. In somecases, the conductive liquid anode or the conductive liquid cathode isassociated with the structure at least in part by surface tensionforces.

In another aspect of the present disclosure, an energy storage devicecomprises an anode comprising a first electronically conductive liquidand a cathode comprising a second electronically conductive liquid,where the device is configured to impede mixing of the electronicallyconductive liquids, and the energy storage device is capable of beingtransported on a truck.

In some instances, the electronically conductive liquids do not mix whenthe device is shaken or tipped. In some cases, the device furthercomprises an electrode separator disposed between the electronicallyconductive liquids. In some instances, the device further comprises aliquid electrolyte, the liquid electrolyte wets the electrode separator,and the electronically conductive liquids do not wet the separator. Insome embodiments, the electrode separator floats in or on theelectrolyte when the device is charged or discharged.

In another aspect of the present disclosure, an energy storage devicecomprises a negative electrode comprising an alkali metal, a positiveelectrode comprising the alkali metal and one or more additionalelements and a liquid electrolyte disposed between the electrodes, wherethe electrolyte is not depleted upon charging or discharging of thedevice, and the energy storage device is capable of being transported ona truck.

At least one of the electrodes can be liquid at an operating temperatureof the device. In some cases, the positive electrode comprises at leasttwo additional elements such that the positive electrode comprises atleast two elements when the positive electrode is fully depleted of thealkali metal. In some instances, the alkali metal is lithium, sodium,potassium, or any combination thereof.

In some cases, the one or more additional elements form an alloy withthe alkali metal or exist in a compound with the alkali metal at anoperating temperature of the device. In some embodiments, the one ormore additional elements have a lower electronegativity than the alkalimetal. In some instances, the electrolyte comprises a salt of the alkalimetal. The operating temperature of the device is any suitabletemperature such that the electrodes are molten (e.g., less than 600°C.).

In another aspect of the present disclosure, an energy storage devicecomprises a liquid metal electrode, a second metal electrode that can bea liquid and an electrolyte disposed between the electrodes, where theelectrolyte is a paste, and the energy storage device is capable ofbeing transported on a truck.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid negative electrode comprising an alkali metal, aliquid positive electrode comprising an alloy of the alkali metal and anelectrolyte disposed between the electrodes, where the electrolytecomprises a salt of the alkali metal and particles and the energystorage device is capable of being transported on a truck.

The particles can comprise alumina or magnesia. In some cases, theelectrolyte is a paste.

In another aspect of the present disclosure, an energy storage devicecomprises a metal anode, a metal cathode and an electrolyte disposedbetween the electrodes, where the anode, cathode and electrolyte areliquids at an operating temperature of the device and the operatingtemperature of the device is less than 500° C., and the energy storagedevice is capable of being transported on a truck.

In some cases, the operating temperature of the device is less than 250°C.

In another aspect of the present disclosure, a method for charging anenergy storage device comprises connecting an external charging circuitto terminals of the energy storage device that is capable of beingtransported on a truck such that an active alkali metal moves from apositive electrode, through an electrolyte, to a negative electrodecomprising a metal having a higher chemical potential than the positiveelectrode.

In some instances, the active alkali metal is lithium, sodium,potassium, or any combination thereof.

In another aspect of the present disclosure, a method for discharging anenergy storage device comprises connecting an external load to terminalsof the energy storage device that is capable of being transported on atruck such that an active alkali metal moves from a negative electrode,through an electrolyte as cations, to a positive electrode where theactive alkali metal forms a neutral metal having a lower chemicalpotential than the negative electrode.

In some cases, the active alkali metal is lithium, sodium, potassium, orany combination thereof.

In another aspect of the present disclosure, an energy storage devicecomprises a liquid metal electrode, an electrolyte and a currentcollector in contact with the electrode, where the current collectorcomprises a material that has a higher wetability with the liquid metalthan with the electrolyte. In some embodiments, the material is a foam.

Energy storage devices of the present disclosure may be used ingrid-scale settings or stand-alone settings. Energy storage device ofthe disclosure can, in some cases, be used to power vehicles, such asscooters, motorcycles, cars, trucks, trains, helicopters, airplanes, andother mechanical devices, such as robots.

Systems, apparatuses and methods of the disclosure may be combined withor modified by other systems, apparatuses and/or methods, such asbatteries and battery components described, for example, in U.S. Pat.No. 3,663,295 (“STORAGE BATTERY ELECTROLYTE”), U.S. Pat. No. 8,268,471(“HIGH-AMPERAGE ENERGY STORAGE DEVICE WITH LIQUID METAL NEGATIVEELECTRODE AND METHODS”), U.S. Patent Publication No. 2011/0014503(“ALKALINE EARTH METAL ION BATTERY”), U.S. Patent Publication No.2011/0014505 (“LIQUID ELECTRODE BATTERY”), U.S. Patent Publication No.2012/0104990 (“ALKALI METAL ION BATTERY WITH BIMETALLIC ELECTRODE”), andU.S. patent application Ser. No. 13/801,333 (“ELECTROCHEMICAL ENERGYSTORAGE DEVICES”), filed on Mar. 13, 2013, which are entirelyincorporated herein by reference.

It is to be understood that the terminology used herein is used for thepurpose of describing specific embodiments, and is not intended to limitthe scope of the present invention. It should be noted that as usedherein, the singular forms of “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. In addition,unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

It should be understood from the foregoing that, while particularimplementations have been illustrated and described, variousmodifications can be made thereto and are contemplated herein. It isalso not intended that the invention be limited by the specific examplesprovided within the specification. While the invention has beendescribed with reference to the aforementioned specification, thedescriptions and illustrations of the preferable embodiments herein arenot meant to be construed in a limiting sense. Furthermore, it shall beunderstood that all aspects of the invention are not limited to thespecific depictions, configurations or relative proportions set forthherein which depend upon a variety of conditions and variables. Variousmodifications in form and detail of the embodiments of the inventionwill be apparent to a person skilled in the art. It is thereforecontemplated that the invention shall also cover any such modifications,variations and equivalents. It is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

What is claimed is:
 1. An electrochemical energy storage devicecomprising a container including a negative electrode, a positiveelectrode and an electrolyte disposed between the negative electrode andpositive electrode, wherein the electrochemical energy storage devicehas a first potential difference between the negative electrode andpositive electrode at a first temperature that is less than about 50° C.and a second potential difference between the negative electrode andpositive electrode at a second temperature of at least about 250° C.,wherein the second potential difference is greater than the firstpotential difference, wherein at least two of the positive electrode,electrolyte and negative electrode are liquid at the second temperature,wherein the container has a surface area-to-volume ratio of less than orequal to about 100 m⁻¹, and wherein the electrochemical energy storagedevice maintains at least about 90% of its energy storage capacity after500 charge/discharge cycles.
 2. The electrochemical energy storagedevice of claim 1, wherein the container contains one or moreelectrochemical cells, and wherein an individual electrochemical cell ofthe one or more electrochemical cells includes the negative electrode,the positive electrode and the electrolyte.
 3. The electrochemicalenergy storage device of claim 2, wherein, over the charge/dischargecycle, a rate of heat generation in the individual electrochemical cellis greater than or equal to about 50% of a rate of heat loss from theindividual electrochemical cell.
 4. The electrochemical energy storagedevice of claim 1, wherein the electrochemical energy storage devicemaintains at least about 90% of its energy storage capacity after 1,000charge/discharge cycles.
 5. An energy storage system, comprising: acontainer comprising one or more energy storage cells, wherein anindividual energy storage cell of the one or more energy storage cellscomprises at least one liquid electrode; and a control system comprisinga computer processor that is programmed to monitor at least oneoperating temperature of the one or more energy storage cells and/or thecontainer, wherein the computer processor regulates a flow of electricalenergy into at least a subset of the one or more energy storage cellssuch that the subset undergoes sustained self-heating over acharge/discharge cycle.
 6. The energy storage system of claim 5,wherein, over the charge/discharge cycle, a rate of heat generation inthe individual energy storage cell is greater than or about equal to arate of heat loss from the individual energy storage cell.
 7. The energystorage system of claim 5, wherein, over the charge/discharge cycle, arate of heat generation in the individual energy storage cell is lessthan or equal to about 150% of a rate of heat loss from the individualenergy storage cell.
 8. The energy storage system of claim 5, whereinthe computer processor monitors the at least one operating temperatureand regulates the flow of electrical energy such that the at least oneoperating temperature is greater than or equal to about 250° C. and theat least one liquid electrode is maintained as a liquid.
 9. The energystorage system of claim 5, wherein the computer processor monitors theat least one operating temperature and regulates the flow of electricalenergy such that over the charge/discharge cycle, the at least oneoperating temperature is greater than or equal to about 250° C.
 10. Theenergy storage system of claim 5, wherein the at least one liquidelectrode comprises (i) lithium, sodium, potassium, magnesium, calcium,or any combination thereof, or (ii) antimony, lead, tin, tellurium,bismuth, or any combination thereof.
 11. The energy storage system ofclaim 5, wherein the individual energy storage cell further comprises anelectrolyte adjacent to the at least one liquid electrode.
 12. Theenergy storage system of claim 11, wherein the electrolyte is liquid,solid or a paste.
 13. The energy storage system of claim 5, wherein theone or more energy storage cells maintain at least about 90% of theirenergy storage capacity after 100 charge/discharge cycles.
 14. Theenergy storage system of claim 13, wherein the one or more energystorage cells maintain at least about 90% of their energy storagecapacity after 500 charge/discharge cycles.
 15. The energy storagesystem of claim 13, wherein the individual energy storage cell has anefficiency of at least about 80%.
 16. The energy storage system of claim15, wherein the individual energy storage cell has an efficiency of atleast about 80% at a current density of at least about 100 mA/cm². 17.The energy storage system of claim 15, wherein the individual energystorage cell has an efficiency of at least about 90%.
 18. The energystorage system of claim 17, wherein the individual energy storage cellhas an efficiency of at least about 90% at a current density of at leastabout 100 mA/cm².
 19. An energy storage device comprising a negativeelectrode, a positive electrode and an electrolyte disposed between thenegative electrode and positive electrode, wherein at least one of thepositive electrode and negative electrode is liquid at an operatingtemperature of the energy storage device that is greater than anon-operating temperature of the energy storage device, wherein theenergy storage device maintains at least about 90% of its energy storagecapacity after 500 charge/discharge cycles, and wherein the energystorage device has an efficiency of at least about 80% at a currentdensity of at least about 100 mA/cm².
 20. The energy storage device ofclaim 19, wherein the energy storage device maintains at least about 95%of its energy storage capacity after 500 charge/discharge cycles. 21.The energy storage device of claim 19, wherein the energy storage devicemaintains at least about 90% of its energy storage capacity after 1,000charge/discharge cycles.
 22. The energy storage device of claim 21,wherein the energy storage device maintains at least about 98% of itsenergy storage capacity after 1,000 charge/discharge cycles.
 23. Theenergy storage device of claim 19, wherein the positive electrode,negative electrode and electrolyte are in a container that has a surfacearea-to-volume ratio that is less than or equal to about 100 m⁻¹. 24.The energy storage device of claim 19, wherein the operating temperatureis greater than or equal to about 250° C.
 25. The energy storage deviceof claim 19, wherein the energy storage device has an energy storagecapacity of at least about 1 kWh.
 26. The energy storage device of claim25, wherein the energy storage capacity is greater than or equal toabout 100 MWh.
 27. The energy storage device of claim 19, wherein aresponse time of the energy storage device is less than or equal toabout 100 milliseconds (ms).
 28. The energy storage device of claim 19,wherein the energy storage device comprises a liquid negative electrode.29. The energy storage device of claim 28, wherein the energy storagedevice further comprises a liquid positive electrode.
 30. The energystorage device of claim 19, wherein the positive electrode, electrolyteand negative electrode are liquid at the operating temperature of theenergy storage device.
 31. The energy storage device of claim 19,wherein the electrolyte is liquid.
 32. The energy storage device ofclaim 19, wherein (i) the negative electrode comprises lithium, sodium,potassium, magnesium, calcium, or any combination thereof, or (ii) thepositive electrode comprises (ii) antimony, lead, tin, tellurium,bismuth, or any combination thereof.
 33. The energy storage device ofclaim 19, wherein the energy storage device is transportable at theoperating temperature.